High-Speed Flickering and Jet Formation in GRS 1915+105

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Title:
High-Speed Flickering and Jet Formation in GRS 1915+105
Physical Description:
1 online resource (177 p.)
Language:
english
Creator:
Lasso Cabrera, Nestor Miguel
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Astronomy
Committee Chair:
Eikenberry, Stephen S
Committee Members:
Hamann, Fredrick
Kargaltsev, Oleg
Bandyopadhyay, Reba M
Reitze, David H

Subjects

Subjects / Keywords:
circe -- electronics -- grs1915 -- gtc -- hawaii-2rg -- hexte -- infrared -- jet -- microquasar -- pca -- qpo -- rms -- rxte
Astronomy -- Dissertations, Academic -- UF
Genre:
Astronomy thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
In this dissertation we study the different phenomena of accretion and relativistic jet formation observed in the microquasar GRS 1915+105. Our final goal is to understand the processes producing the relativistic outflows, as well as their relation with the inflow mechanisms. Initially, we analyze X-ray emission (RXTE PCA and HEXTE) from GRS 1915+105 during and after an X-ray/radio plateau epoch. The high signal-to-noise levels in our observations allow the first published measurement of quasi-periodic oscillations (QPO) RMS values using RXTE/HEXTE data. We find that the spectral energy distribution of the QPO strongly indicates an origin in the hard non-thermal emission component, suggesting a second spectral component to the hard non-thermal X-ray emission. Given the association of the QPOs with the observed jet activity in GRS 1915+105, we suggest that this additional non-thermal X-ray spectral component may be directly linked to the relativistic jet formation process. We also analyze simultaneous X-ray (RXTE/PCA) and near-IR (Palomar 200-inch) observations from the microquasar GRS 1915+105 during two similar low/hard state epochs and two different high X-ray variability epochs – X-ray classes alpha and beta. The X-ray to IR cross-correlation function (CCF) shows that both low/hard state observations as well as the class beta observations present little or null interaction between the X-ray and IR fluxes, while the class alpha observations present a strong correlation between the X-ray (inner accretion disk) and the IR (compact jet) light curves. We also use the X-ray to IR CCF to study the relative evolution of the two signals and find no significant evolutionary track in any of the epochs. Simulated IR light curves confirm the results of the CCF, showing a flickering IR emission during the class beta high X-ray variability period that strengthens ~10 s after every X-ray subflare. The existence of a flickering IR emission with frequencies in the range 0.1 to 0.3 Hz that is strongly correlated with the X-ray emission allow us to place the origin of the IR emission in a synchrotron emitting relativistic jet with the IR launch site located at ~0.02 AU from the accretion disk. These results will be especially relevant for constraining the current models of relativistic jet production in GRS 1915+105 and other microquasars. The second part of this work is dedicated to overcoming the limitation in the acquisition of high time resolution infrared data of microquasars. We introduce the Canarias InfraRed Camera Experiment (CIRCE), a new IR instrument for the 10-meter Gran Telescopio Canarias (GTC). Among other properties, CIRCE is specifically designed for the observation of relativistic jet events in microquasars, and along with the capabilities of the GTC, will enable us to observe any microquasar in the J, H, and K IR bands, with a time resolution of ~12 Hz and a signal-to-noise level never achieved before. We plan to use CIRCE in the future to confirm the final results of the jet production study of this dissertation. We present the electronics design of CIRCE, including the housekeeping electronics, the Logic Control Unit (LCU), and the readout electronics. We also present the result of the analysis of the image quality tests performed on the CIRCE optical system.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Nestor Miguel Lasso Cabrera.
Thesis:
Thesis (Ph.D.)--University of Florida, 2012.
Local:
Adviser: Eikenberry, Stephen S.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2013-02-28

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UFRGP
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Applicable rights reserved.
Classification:
lcc - LD1780 2012
System ID:
UFE0044494:00001


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Tomyfamilyforbeingalwaysthere 3

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Thanksgoouttoallthepeoplewhohavehelpedmethroughthislongjourney.Here,Iincludethosedirectlynamedhereandthose,thatbecauseofthelimitedextensionofthesepages,cannotbeincluded.Iwouldliketostartbythankingmyadvisor,ProfessorStephenEikenberry,forhisguidance,hissupport,hisfriendship,hisoptimism.Iwouldalsoliketothankhimfortransferringtomehisenthusiasmaboutmicroquasarsandinstrumentation,andespeciallyforlettinganinexpertengineerparticipatesincedayoneinsuchabiginstrumentationprojectasCIRCE.Also,Iwanttothankhimforhisguidanceaboutmyacademiccareerandforalwaysremainingcalm,especiallyinthislastyear.IwouldalsoliketothankDr.RebaBandyopadhyayandDr.NicholasRainesfortheircontinuousacademicandnon-academicadvice.Theycouldeasilybeconsideredasco-advisorinthescienticandinstrumentalportionofthiswork.Ithanktheothermembersofmycommittee,Dr.OlegKargaltsev,Dr.FredHamann,andDr.DavidReitzefortheirusefulinputanddiscussions.Ialsothankallthepeoplewhothroughtheyearshaveformedpartofourscienticgroup.Theirdiscussionshelpedmetogrowasascientistandtonavigatethroughmygraduateschoolyears.Finally,Ialsowanttothankthemanyengineersfromthefourthoorwhohavegivenmetheiradvice.Inadditiontomyacademicmentors,noneofthiswouldhavebeenpossiblewithoutthesupportofmygoodfriends.IwillneverforgetthosepricelessmomentswithDimitriVeras,CurtisDeWitt,SunMiChung,JesusMartinez,andmywifea.k.atheTopChefGangandallotherswhooccasionallyjoinedus.Iamthankfulforthelongextendeddinners,thebeachtrips,theunexpectedadventures,andespeciallyforlettingmebepartoftheirlives.IalsothanktheSpanishtribe,fromtheonesthatwelcomedmetotheoneswhoIhavewelcomed.Theyhavebeenlikeasmallfamily,alwaysmakingthisprocessmoreenjoyable.IcannotforgettothanktoallthepeoplewhohaveplayedsoccerwithmeduringalltheseyearsinGainesville,especiallymyteammates.Theyhavegivenmethatpointofsanitythathasallowedmetosurvivemygraduateschool 4

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THANKSTOALL! 5

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page ACKNOWLEDGMENTS .................................. 4 LISTOFTABLES ...................................... 9 LISTOFFIGURES ..................................... 10 ABSTRACT ......................................... 13 CHAPTER 1INTRODUCTION ................................... 15 2GRS1915+105ANDJETFORMATIONPROCESSES .............. 18 2.1X-rayBinarySystems ............................. 18 2.2GRS1915+105 ................................. 22 2.3X-rayLightCurves ............................... 25 2.4Low-FrequencyQuasiperiodicOscillations(LFQPOs) ........... 27 2.5LongWavelengthFlaringandJetFormationProcesses .......... 30 3HARDX-RAYOBSERVATIONSOFHIGH-SPEEDFLICKERINGANDJETFORMATIONINGRS1915+105 .......................... 33 3.1IntroductiontoGRS1915+105 ........................ 33 3.2Observations .................................. 36 3.3X-rayLightCurves ............................... 37 3.4QPOPowerSpectralFeatures ........................ 37 3.5X-rayEnergySpectra ............................. 38 3.6FractionalQPORMSSpectra ......................... 41 3.7Discussion ................................... 45 4SIMULTANEOUSX-RAYANDNEAR-INFRAREDOBSERVATIONSANDJETFORMATIONINGRS1915+105 .......................... 51 4.1IntroductiontoSimultaneousMulti-WavelengthObservations ....... 52 4.2ObservationsandDataReduction ...................... 55 4.3SimultaneousX-rayandIRLightCurves ................... 57 4.4MeanX-raytoIRCross-correlation ...................... 58 4.5CCFEvolution ................................. 61 4.6SimulatedIRlightcurves ........................... 64 4.7Summary .................................... 72 5CIRCEANDTHEOBSERVATIONOFJETSINMICROQUASARS ....... 74 5.1CIRCE ...................................... 75 5.1.1OpticalDesign ............................. 77 6

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........................... 78 5.1.2.1FilterBox ........................... 81 5.1.2.2FocalPlaneMechanism ................... 83 5.2SciencewithCIRCE .............................. 84 5.3ObservationofJetsinMicroquasars ..................... 85 5.3.1PhotometricStudies .......................... 85 5.3.2SpectroscopicStudies ......................... 87 5.3.3PolarimetricStudies .......................... 88 5.3.4CIRCEObservationsofGRS1915+105 ............... 88 5.4Summary .................................... 89 6READOUTELECTRONICSFORCIRCE:INITIALDESIGNANDFASTPHOTOMETRYDRIVERS ............. 91 6.1InitialDesign .................................. 93 6.1.1ArrayControllerSubsystem(MCE-3) ................. 93 6.1.2BiasBoard ............................... 94 6.1.2.1Opto-Isolation ........................ 94 6.1.2.2DCBiasGeneration ..................... 95 6.1.2.3ESDProtection ........................ 95 6.1.3PreampBoard ............................. 96 6.1.4FanoutBoardColdClocking ...................... 97 6.1.5Electro-StaticProtection ........................ 97 6.1.6HAWAII-2OutputModes ........................ 98 6.1.7Firmware ................................ 98 6.1.8ArrayReadout ............................. 100 6.2FastPhotometryDrivers ............................ 102 6.2.1FastPhotometry ............................ 102 6.2.2FastPhotometryModePossibilities .................. 104 6.2.2.1Option1:EightOutputPlusFirmwareModications ... 104 6.2.2.2Option2:EightOutputPlusFirmwareModicationsPlusMCE-3Modications .................... 105 6.2.2.3Option3:SingleOutputPlusFirmwareModicationsPlusMCE-3Modications .................. 106 6.2.2.4Option4:EightOutputPlusFirmwareModicationsPlusMCE-3ModicationsPlusRewiring ............ 107 6.3Summary .................................... 107 7CIRCEELECTRONICS:FINALDESIGNANDIMPLEMENTATION ....... 117 7.1TopLevelandDewarCableMaps ...................... 119 7.1.1TopLevelCableMap .......................... 120 7.1.2DewarCableMap ............................ 123 7.2HousekeepingElectronics ........................... 123 7.2.1TemperatureandPressureControl .................. 125 7.2.2MovingMechanisms .......................... 129 7

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................. 134 7.3LogicControlUnit ............................... 135 7.4ReadoutElectronics:FinalDesign ...................... 143 7.5ISDECBoardPerformance .......................... 147 7.6Summary .................................... 149 8OPTICALSYSTEMIMAGEQUALITYTEST .................... 152 8.1SurfaceRoughnessTest ............................ 153 8.2ImageQualityTest ............................... 155 8.2.1OpticalAberrations ........................... 156 8.2.2FocalPlaneFieldCurvature ...................... 157 8.2.3FWHMMeasurements ......................... 158 8.2.4OpticalSystemFlexureTest ...................... 160 8.3Summary .................................... 161 9CONCLUSION .................................... 163 APPENDIX:CALCULATIONOFFRACTIONALRMSERRORBARS ......... 168 REFERENCES ....................................... 170 BIOGRAPHICALSKETCH ................................ 177 8

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Table page 3-1ObservationSummary ................................ 37 3-2SpectralFittingSummary .............................. 41 3-3ModelsoftheX-rayEmissionofGRS1915+105 ................. 49 4-1IRsimulatedlightcurves:KStestandMonteCarlosimulationresults ..... 65 4-2ParameteroftheIRsimulatedlightcurves ..................... 68 6-1ReadoutTimes .................................... 105 6-2FrameRates ..................................... 107 7-1MCE-3vsISDECFrameRates ........................... 147 8-1MirrorsSurfaceRoughness ............................. 154 8-2ImageQuality ..................................... 159 9

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Figure page 2-1GalacticMicroquasars ................................ 20 2-2MicroquasarDiagram ................................ 21 2-3LMXBstates:Evolutionoftheaccretionandejectioncomponents ....... 23 2-4Classlightcurveandcolordiagram ....................... 28 2-5Classlightcurveandcolordiagram ....................... 28 2-6Classlightcurveandcolordiagram ....................... 28 3-1PowerSpectrum ................................... 39 3-2FractionalQPORMS ................................. 43 3-3CombinedQPORMSSpectra ........................... 45 3-4StandardandLasso-Cabreraetal.modelsoftheX-rayemissionofGRS1915+105 48 4-1SimultaneousGRS1915+105classX-rayandclassBIRaresobservations 56 4-2SimultaneousGRS1915+105classX-rayandclassCIRaresobservations 56 4-3MeanCCFofLow/HardStates ........................... 58 4-4MeanCCFofthe1997HighclassX-rayVariabilityStates ........... 59 4-5MeanCCFofthe2002HighclassX-rayVariabilityStates ........... 60 4-6CCFEvolutionDuringLow/HardStates ...................... 62 4-7CCFEvolutionDuringHighX-rayVariabilityStates ................ 63 4-8X-rayandSimulatedIRLightCurvesandCCFs .................. 66 4-9X-rayandSimulatedIRLightCurvesandCCFs .................. 67 4-10DiagramofJetDistancesandPlasmaBlobDiameters .............. 71 5-1CIRCETechnicalSpecicationsandObservingModes .............. 76 5-2CIRCEOpticalLayout ................................ 77 5-3CIRCEOpticalBench ................................ 79 5-4CIRCEOpticalBenchCurrentState ........................ 79 5-5CIRCEDewarDesign ................................ 80 10

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..................................... 80 5-7CIRCEFilterBox ................................... 82 5-8CIRCEFilterBoxImage ............................... 82 5-9CIRCEFocalPlaneMechanism ........................... 83 6-1Bias&PreampBoards ................................ 95 6-2BiasBoard ...................................... 96 6-3HAWAII-2Readout .................................. 99 6-432Outputs2048x2048ArrayReadoutSchematic ................. 101 6-5HAWAII-2FrameSizes ............................... 106 6-6Option1:512x512SubarrayReadoutSchematic ................. 109 6-7Option1:256x256SubarrayReadoutSchematic ................. 110 6-8Limited32Outputs256x256SubarrayReadoutSchematic ........... 111 6-9Option2:256x256ArrayReadoutSchematic ................... 112 6-10Option3:512x512ArrayReadoutSchematic ................... 113 6-11Option3:256x256ArrayReadoutSchematic ................... 114 6-12Option4:512x512ArrayReadoutSchematic ................... 115 6-13Option4:256x256ArrayReadoutSchematic ................... 116 7-1ExampleCIRCECableDocument ......................... 120 7-2CIRCECableMapTopLevel ............................ 122 7-3CIRCEDewarCableMap .............................. 124 7-4WarmupBoxCableMap ............................... 128 7-5LCU:Temperature&PressureChassisCableMap ................ 130 7-6LCU:MotorChassisCableMap .......................... 131 7-7LCU:Temperature&PressureChassis ...................... 133 7-8LCU:MotorChassis ................................. 133 7-9ConnectorVacuumPlate .............................. 136 7-10FanoutBoardSchematics .............................. 137 11

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................................ 139 7-12LCURackRearView ................................ 140 7-13LCU:ThermalEnclosureTemperatureControlCableMap ............ 141 7-14LCURackDesign .................................. 142 7-15ReadNoisevs.PixelRate .............................. 151 7-16ReadNoisevs.ExposureTime ........................... 151 7-17Singlevs.DoubleFlexCableReadNoiseatDifferentPixelRates ........ 151 8-1MirrorsDiffractionPatterns ............................. 155 8-2PinholeMask ..................................... 156 8-3OpticalAberrations .................................. 157 8-4FocalPlaneFieldCurvature ............................. 158 8-5ImageQuality ..................................... 160 12

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2 isfocusedonthedescriptionofmicroquasarsandaccretion/ejectionprocesses,givingparticularemphasistothecaseofGRS1915+105.Chapter 3 isdedicatedtotheanalysisofquasi-periodicoscillations(QPOs)inthehardX-rayemissionofthemicroquasarGRS1915+105.WeprovideevidenceforthepresenceofanewcomponentintheX-rayemissionofGRS1915+105,andsuggestanoriginofthenewcomponentinthejet-formingregion.ThischapterhasbeensubmittedtotheAstrophysicalJournal(Lasso-Cabreraetal.insubmitted).Chapter 4 isastudyoftherelationbetweentheIR(ejection)andX-ray(accretion)signalsofGRS1915+105.Weproduceadetailedcross-correlationstudyofsimultaneousIRandX-raylightcurves.InChapter 5 ,weintroduceCIRCEanditscapabilitiesfortheobservationofjet-producingregions.Chapter 6 isdedicatedtothedescriptionoftheinitialdesignofthereadoutelectronics,andtheimplementationofthefast-photometrymodeinCIRCE.ThischapteristhecombinationoftwoSPIEproceedings( LassoCabreraetal. 2008 & LassoCabreraetal. 2010 ).Chapter 7 includesadescriptionofthenaldesignofthereadoutelectronicsandthehousekeepingelectronics.Finally,inChapter 8 wepresenttheresultsoftheimagequalitytestsperformedontheopticalsystemofCIRCE.TheseresultshavealreadybeenpresentedintheIVSciencewiththeGTCconferenceandsubmittedasaproceedingtothe2012SPIEconference(Lasso-Cabreraetal.2012). 17

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Giacconietal. 1962 ).IntheoutburstphaseofLMXBs,matteristransferredfromthedonorstartotheblackholethroughanopticallythickaccretiondisk.Duringthespiralinfallprocess,thedensityandtemperatureofthegasincreasesdrasticallywithproximitytothecompactobject.TheinnerpartoftheaccretiondiskemitshighluminosityX-rays(T2keV),illuminatingthewholesystem.However,morethan30%ofLMXBsaretransient,andspendmostoftheirtimeinaquiescentstate( Tanaka&Shibazaki 1996 ).OutburstlengthsinLMXBsrangefrommonthsto20yearsforGRS1915+105beforereturningtothequiescentstate.TypicalX-rayluminositiesduringtheoutburstarebetween1037and1039ergss1,whileLMXBsinthequiescentstatearefainter,withupperlimitsintherangeof1032ergss1( Asaietal. 1998 ).TherearemorethanahundredLMXBsknowninourGalaxy( Liuetal. 2007 )andhundredsoftheminexternalgalaxies( Fabbiano 2006 ; Evansetal. 2010 ).Currently,only20blackholebinarysystemshavebeendynamicallyconrmedintheGalaxy,with17ofthemhavingalow-masscompanion( Remillard&McClintock 2006 ; Casares 2010 ).Aschematicdiagramofthe20dynamicallyconrmedLMXBsisshowninFig. 2-1 ,wherediskandcompanionstarssizes,distances,andtemperatureareshowntoscale.Onveryrareoccasions,LMXBsalsoshowejectioneventssimultaneouslywiththeaccretionevents.Todate,tenLMXBshaveexhibitedthepresenceofrelativisticjets( Fenderetal. 2004 ).Theejectioneventsareobservedintheformofrelativisticsynchrotroninfrared(IR)andradiojets.Inthisway,LMXBsdisplaymanyofthecharacteristicsseenindistantquasars,butonasmallertimescale( Mirabel&Rodrguez 1999 ).Theirsimilaritytoquasarshasgainedtheseobjectsthenameofmicroquasars.Theshorttimescalesexhibitedbymicroquasarsminutestodaysratherthanyearsin 19

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Schematicdiagramofthe20dynamicallyconrmedblackholebinaries.Seventeenhavelowmasscompanions(i.e.starswithmasseslessthanabout3solarmasses),andthethreeonthetophavehighmasscompanions.Thecolorscaleforthe17objectswithlowmasscompanionsrepresentsthetemperatureofthestar(CygX-1,LMCX-1,andLMCX-3allhavecompanionswhichareconsiderablyhotter).ReprintedbypermissionfromOrosz,Jerome.( quasarsprovideusefulopportunitiesforobservingthesephenomenaandimprovingourunderstandingoftheaccretionandejectionmechanismsonmoreaccessibletimescales.Fig. 2-2 showsadiagramofamicroquasarwithallthedifferentelementsofthesystemlabeled.Thestudyoftheaccretionandejectionprocessesinthesedistantobjectsisaccomplishedthroughtheobservationofchangesinluminosityatdifferentwavelengths. 20

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MicroquasarDiagram.ReprintedbypermissionfromHynes,Rob.( InLMXBs,changesinluminosityaredirectlyrelatedtothestateoftheLMXBs,i.e.,withthephysicalprocesseshappeningintheobject.Forexample,thelevelandenergyoftheX-rayluminosityaredirectlyrelatedwiththeinnerradiusandtemperatureoftheaccretiondisk( Bellonietal. 1997 );oranincrementintheIRand/orradioluminosityimpliesanejectionevent( Mirabel&Rodrguez 1996 ; Eikenberryetal. 1998a ).Throughanalysisoftheluminosityatdifferentwavelengths,threestatescommontoallmicroquasarshavebeenfound:quiescent,soft,andhardstates( Fender&Belloni 2004 ).Thequiescentstateisthedormantphaseinwhichmicroquasarsspendmostoftheirlife.Inthequiescentstate,theaccretionandejectionarereducedtoaminimum,andtheinneraccretiondiskisnonexistentwiththeouterdiskemittingintheoptical/UVwavelengths.ThesoftstaterepresentsthestatedominatedbyasoftblackbodyX-rayspectrumwithhighsoft(<10keV)X-rayluminosity.Thereisnopresenceofjets,andtheinneraccretiondiskisfullydevelopedwiththeinnerradiusclosetoitsminimum 21

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Vilhuetal. 2001 ).Thepresenceoftheinneraccretiondiskisappreciableinthehardstate,althoughitisnotfullydeveloped.SimultaneousX-ray,IR,andradioobservationsofthehardstateshowdirectevidenceofadisk-jetconnection( Mirabeletal. 1998 ).Thequiescent,soft,andhardstatesarecommontoallmicroquasarsalthoughnotunique.Somesourcesexhibitotherintermediatestatesthatseemtobetransitionstatesbetweenthesoftandhardstates.SeeFig. 2-3 foradetaileddiagramofthecycleofstatesinmicroquasars.WhilethequiescentandsoftstatesarecommontoLMXBsandmicroquasars,thehardstatethejetstateisdistinctiveofmicroquasars.ThedifferentiationbetweenLMXBsandmicroquasarsisbasedontheexhibitionornotofthehardstateatsomepointoftheirlifetimes. Mirabel&Rodrguez 1999 )makesGRS1915+105themostsuitablelaboratorytostudytheintricatemechanismspresentintheaccretion/ejectionprocessesofmicroquasars.Unliketheothermicroquasars,GRS1915+105hasnotreturnedtothequiescentstateafterafewyears,andhasbeenactivesinceitsdiscoveryasanX-raytransientin1992( Castro-Tiradoetal. 1994 ).GRS1915+105isthelongestcontinuouslyactiveGalacticmicroquasartodate,andhasprovideduswithatreasured 22

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Representationoftheobservationalpropertiesoftheevolutionofaccretion/ejectioncomponentsinGalacticblack-holebinaries.ReprintedbypermissionfromBelloni,Tomaso.(

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Mirabel&Rodriguez 1994 ).LocatedintheGalacticplaneatadistanceof11kpc,theorientationofthe0.9cspeedjetspresentsaninclinationof662( Fenderetal. 1999 ).GRS1915+105istheheaviestknownGalacticmicroquasar,withablackholemassofMBH=14.04.4M( Harlaftis&Greiner 2004 ).TheShakura-Sunyaevthindiskmodel( Shakura&Sunyaev 1973 )predictsforthisobjectanaccretiondiskinnerradiusof42kmforanon-spinningblackhole(Schwarzschildradius),or21kmforatheoreticalmaximallyspinningblackhole(Kerrradius-1150timespersecond).Theinnerradiusofanyaccretingblackholecanbemeasuredusingaccuratemodelsoftheemissionoftheinnermostpartoftheaccretiondisk.InthecaseofGRS1915+105,thedistancebetweenthecenteroftheblackholeandtheinnermoststablecircularorbitvariesdependingonthestateofthemicroquasar,withminimumradiirangingfrom21to25km.Suchsmalldistancesinfervaluesofthespinningratebetween0.8and1ofthetheoreticalmaximumspinningblackhole( Narayanetal. 2008 ).Thefastrotationoftheblackholeisreplicatedtosomeextentbytheinneraccretiondisk.Thespiraling-inmatterreachesthemaximumtemperatureintheveryinnerpartofthedisk,producingamaximumofemissioninthesoftX-ray(0.7-10keV)withluminositiesrangingfrom1038to6x1039ergss1( Greineretal. 1996 ).GRS1915+105isoneofthebrightestX-rayobjectsinthesky.TheX-rayspectrumofGRS1915+105isbestttedwithasoftthermalblackbodycomponentplusahardpowerlaw.ThesoftblackbodycomponentischaracteristicofafastrotatingaccretiondiskwhilethehardpowerlawcomponentisproducedbythermalComptonizationofseedsoftblackbodyphotons.AsaLMXB,thestellarmassblackholeoftheGRS1915+105binarysystemisaccretingmatterfromadonorstar.ThelowmasscompanionstarofthemicroquasarGRS1915+105wasunveiledthroughidenticationofabsorptionlinesintheIRspectrum.ThecompanionstarwasclassiedasaK-MIIIstarwithamassrange 24

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Greineretal. 2001 ).OneofthemajordifcultiesfacedinthestudyofGRS1915+105isthemoderatedluminosityoftheobjectintheinfraredandvisibleregimes.ThelocationofGRS1915+105intheGalacticplaneat11Kpcawaytranslatesintoahighextinctionatallwavelengths,withahydrogencolumndensityalongthelineofsightof6x1022cm2( Munoetal. 1999 ).AlthoughthehighlyactiveX-rayandradiowavelengthspartiallyexceedtheextinction,attheradiopositiontheopticalcounterparthasonlybeendetectedintheIbandat23.4mag,withmagnitudesfainterthan26fortheB,V,andRbands( Boeeretal. 1996 ).TheIRregimealsopresentsaconsiderableextinctionwithapproximatevaluesof17,14,and13magnitudesfortheJ,H,andKbandsrespectively( Mahoneyetal. 1997 ).TheintermediatemagnitudesshownintheIRemissionlimittheobservationofthesource,preventingthestudyofhighlyvariablecomponentsintheIRsignal. Jahodaetal. 1996 ),whichprovidesalargecollectionareaandhightime 25

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Rothschildetal. 1998 ),whichischaracterizedbyabroad-band(15-250keV)coveragealsowithhightimeresolution(8s);andthewide-angleAll-SkyMonitor(ASM)( Levineetal. 1996 ).TheRXTEsatellitehasbeenapricelessinstrumentforX-rayobservationsofGRS1915+105,accountingformorethanathousandobservationsthroughtheapproximately20yearoutburstofthesource.AlthoughothermicroquasarsreplicateisolatedstatesofGRS1915+105,theX-rayvariabilityexhibitedbyGRS1915+105hasnocomparisonwithanyothersource.RXTEsatellitesemi-continuousmonitoringoftheobjectallowedaclassicationofitsX-rayemissioninto12separateclasses( Bellonietal. 2000 ),withalateraddition( Klein-Woltetal. 2002 ),basedonX-raycolorsandcountrates.Eachoneoftheseclassescanlastfromminutestodays,onlyshowingpreferencetoremaininthelong-lastingclass.Theobservedoccupationtimeofclassisseveraltimeslargerthananyotherclass.Thetransitionsamongclassesalternatewithnoregularpatternobserved.Despitethecomplicatedlightcurvesofeachclass,allclassescanberepresentedasarepetitivecycleoftransitionsbetweenthreedifferentstates:A,B,andC( Bellonietal. 2000 ; Fender&Belloni 2004 ).StatesAandBaredominatedbyasoftdiskcomponent,withstateBhavingahigherdisktemperatureandcountratethanstateA.StateBalsoshowsaweakcorona.Nojetsarepresentduringthesestates.StateCcorrespondswiththehardstateofmicroquasars.Astrongcoronaandajetarepresent,andtheX-rayradiationisdominatedbyaatpowerspectrumwithlowcountrate.BidirectionaltransitionsamongallthreestateshavebeenobservedwiththeexceptionofthetransitionfromstateCtoB.Thisworkisbasedontheanalysisofthreeoftheclasses:class,class,andclass.Thesethreeclassesseemtobeconsistentlylinkedwiththepresenceofquasi-continuousIRandradiosynchrotron-emittingrelativisticjetoutows( Eikenberryetal. 1998a ; Mirabeletal. 1998 ; Fender&Pooley 1998a ; Klein-Woltetal. 2002 ). 26

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2-4 ).Thecountrateislow(<10Kcts/s)withanabsenceofstrongvariability.TheX-rayspectrumischaracterizedbythepresenceofaatpowerlaw. 2-5 ).Long1000sstateCdips(<5Kcts/s)alternatewithvariabilityperiods.Thevariableportionstartswithastrongare(>20Kcts/s)thatisfollowedbyasetofsmallerares(10Kcts/s).DuringthisparttheobjectalternatesbetweenstateBaresandstateCshortdips. 2-6 ).Thelong500sdipsstartinthestateC(<10Kcts)changingrapidlytothestateA(10-20Kcts)afterthebigsoftspike.ThesourcetransitionsthenfromstateAtostateB(40Kcts),beforegoingintoalonghighvariabilityperiod.Thevariableperiodischaracterizedforthealternationbetweenstrongspikesandshortdips.WhilethedipsareinthestateA,therisingpartofthespikesareinthestateB,andthefallingpartinthestateC,i.e.,arepetitiveA-B-Ccycle. Leahyetal. 1983 ).PDSofGRS1915+105showaverycomplexstructurewithseveralcontinuumnoisecomponents( Morganetal. 1997 ).Theyalsoexhibitthepresenceoftransientquasi-periodicoscillations(QPOs)dependingonthestateofthemicroquasar.Lowfrequency(1-30Hz)andhighfrequency(100-450Hz)QPOs(LFQPOs-HFQPOs)arecharacteristicoftheverysoftandintermediatestates,withLFQPOs(0.01-20Hz)beingpredominantlyseeninthesoftandhardstates( vanderKlis 2004 ).MostofLFQPOanalysesarerestrictedtothestateCbecauseofthehighsignal-to-noiselevelprovidedbythelonglightcurvesofthisstate.ThestudyofLFQPOsprovidesveryrelevantinformationforunderstandingthephysicalprocesseshappeningintheproximity 27

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Exampleclasscolordiagram(top)andlightcurve(bottom).Inthecolordiagram,HR1=B/AandHR2=C/A,whereA,B,andCarethevaluesoftheuxesinthePCAenergybands2-5,5-13,and13-60keV.ReprintedbypermissionfromBelloni,Tomaso.2000. Bellonietal. ( 2000 ). Exampleclasscolordiagram(top)andlightcurve(bottom).Inthecolordiagram,HR1=B/AandHR2=C/A,whereA,B,andCarethevaluesoftheuxesinthePCAenergybands2-5,5-13,and13-60keV.ReprintedbypermissionfromBelloni,Tomaso.2000. Bellonietal. ( 2000 ). Exampleclasscolordiagram(top)andlightcurve(bottom).Inthecolordiagram,HR1=B/AandHR2=C/A,whereA,B,andCarethevaluesoftheuxesinthePCAenergybands2-5,5-13,and13-60keV.ReprintedbypermissionfromBelloni,Tomaso.2000. Bellonietal. ( 2000 ). 28

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Varniereetal. 2007 ).EnergydependenceanalysesrevealthattheuxoftheLFQPOsismaximuminthesameenergyrangethantheblackbodyradiation,associatingdirectlytheQPOswiththephysicalprocessesoccurringintheinneraccretiondisk( Mirabel&Rodriguez 1994 ; Bellonietal. 1997 ).However,ndingadirectrelationbetweenthelowfrequencyoftheQPOsandthehighlydynamicalKeplerianfrequenciesoftheaccretionowshasbeenprovedanarduoustask.SeveralrelationshasbeenfoundbetweenQPOsandphysicalparametersofthesystem.Forexample,thecentroidfrequencyiscorrelatedwiththeuxoftheinneraccretiondisk( Markwardtetal. 1999 ; Munoetal. 1999 ),andwiththelengthofthestateCinterval( Trudolyubovetal. 1999 );thecentroidfrequencyhasalsobeencorrelatedwiththepower-lawphotonindex( Vignarcaetal. 2003 ).However,laterworkseemstoindicateahardernon-blackbodyoriginoftheQPOs( Zdziarskietal. 2005 ; Sobolewska&Zycki 2006 ; Miklesetal. 2006 ; Rodriguezetal. 2008 ).TheenergydependenceoftheQPORMSvariabilityhasbeenobservedtobeharderthantheblackbodyemission( Zdziarskietal. 2005 ; Sobolewska&Zycki 2006 ; Rodriguezetal. 2008 ).ThehardQPOspectradecoupletheQPOsfromtheblackbodyemission,leavingthehardX-ray(E>10keV)astheenergyrangefromwhichtheQPOarises.Theobservationalevidenceyieldstwopotentialscenariosfortheoriginoftheoscillations:intherstone,theoscillationisproducedintheinneraccretiondiskandtransferredtohigherenergiesthroughthenon-destructiveComptonizationoftheoscillatingseedphotonsonthecorona;inthesecondone,anoscillatorytypeofinstabilityisactingintheComptonizingcorona.Softseedphotonsareupscatteredatthesametimethattheoscillationisintroducedintheradiation.InbothscenariostheQPOshavehardspectra,aswellasthetemperatureandradiusoftheinnerdiskcontrolthepropertiesoftheQPOs. 29

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Nowak&Wagoner 1993 ).Thedriftblobmodel(DBM)assumedblobsspiralinginwardthroughtheinneraccretiondisktoexplaintheformationoftheQPOs( Bottcher&Liang 1998 ).Theglobaldiskmodel(GDM)suggestedthattheoriginoftheLFQPOsisassociatedwithgravitationalinteractionsbetweentheblackholeandtheaccretiondisk( Titarchuk&Osherovich 2000 ).Insomecases,theoriginoftheLFQPOsisexplainedthroughtherelationbetweentheQPOfrequencyandafrequencyassociatedwiththeinneraccretiondisk,e.g.,magnetoacousticalfrequency( Titarchuk&Fiorito 2004 )orKeplerianfrequency( Trudolyubovetal. 1999 ).ThelattermodelrelatedtheviscoustimescaleatacertainradiuswiththeKeplerianfrequencyatthesameradius.ThesearchforamodeltoexplaintheformationoftheQPOsgoesbeyondtheexplanationofsomepropertiesoftheQPOs.TheinterpretationoftheQPOformationcannotbeisolatedfromtherestofthesystem,hencetheQPOmodelneedstobeintegratedwithinamorecomplexglobalmodelthatexplainsthewholeaccretion-ejectionsystem.Forexample,theAccretionEjectionInstability(AEI)modelexplainstheaccretiontowardtheblackhole,linkstheaccretionwiththeemissionofcompactjets,andexplainstheLFQPOsthroughmagneticinstabilitiesandKeplerianmotion( Tagger&Pellat 1999 ; Varniereetal. 2002 ; Tagger&Varniere 2006 ). Mirabel&Rodriguez 1994 ; Pooley 1995 ; Fenderetal. 1997 ; Eikenberryetal. 1997 ; Mirabeletal. 1998 ).Simultaneousobservationsofthesourceatseveralwavelengthshaveprobedascenarioofdisk-jetcoupling,whereinX-raylightcurvescorrespondtoaccretion,andIRandradiolightcurvestoejection 30

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Eikenberryetal. 1998a ; Mirabeletal. 1998 ).TheIRandradiooutowsareconsistentwithquasi-continuouscollimatedjetseventsarisingfromarelativisticsynchrotron-emittingplasma.Thequasi-continuousoutoweventsaretypicallyassociatedwiththestateCofthemicroquasar,i.e.,withthehardX-rayplateau,andthereforewiththepresenceofQPOs( Klein-Woltetal. 2002 ).Therelationbetweentheemissionofahotplasma,withtherecessionoftheinnerradiusoftheaccretiondiskduringthehardX-raystate,seemsconsistentwithascenariowheretheinneraccretiondiskisejectedduringthehardX-raydips,andreplenishedduringthesoftstatesAand/orB.Also,duringahardX-raydip,highfrequency(25s)ickeringhasbeenobservedintheIRradiationemittedfromthebaseofthejet( Eikenberryetal. 2008 ).Thisobservationsupportstheideaofanoscillatingjet,andaccentuatestherelationbetweentheoscillatingjetandtheQPOsoccurringsimultaneouslyduringthehardX-raystate.Inadditiontothequasi-continuousoutowevents,GRS1915+105hasdisplayedthreedifferenttypesoflongwavelengtharesduringitsactivelife:classesA,B,andC.AllthreeclassesofaresareobservedconsistentlyafterlonghardX-raydips,emphasizingtherelationbetweenthehardX-raystatewiththeejectionevents.InthisworkwefocusourattentioninclassesBandC,thoseshowingIRares.Followingthereisadescriptionofthethreeclassesofares: Mirabel&Rodriguez 1994 ),classAaresaretheleaststudiedbecauseofthelongrecurrenceintervals,onceeveryoneortwoyears. Fenderetal. 1997 ; Eikenberryetal. 1998a ),andsynchrotronorigin.IRandradiooutowsshowatimedelay,withIRarescomingrst,compatiblewithadiabaticexpansion/coolingoftheejectedplasma( Fenderetal. 1997 ; Mirabeletal. 1998 ).Thedelaycanbeexplainedasthetransitionfromanopticallythicktoanopticallythinsynchrotron-emittingplasmaatlongerwavelengths.ClassBaresareassociatedwithX-rayclasslightcurves,wheretheIRareispresumablytriggeredbythestrongspikeafterthedip( Eikenberry 31

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, 2000 ; Rothsteinetal. 2005 ; Miklesetal. 2006 ).Thoseobservations( Fenderetal. 1997 ; Eikenberryetal. 1998a ; Mirabeletal. 1998 )areconsideredtherstdirectobservationofrelativisticjetformingeventsinmicroquasars. Eikenberryetal. 2000 ).Inthiscase,classCaresareassociatedwithX-rayclasslightcurves,wheretheIRexcessseemstoarisemarginallyearlierthantherstbigX-rayspike( Eikenberryetal. 2000 ; Rothsteinetal. 2005 ; Miklesetal. 2006 ).WithinaclassCare,occasionalIRmicro-areshavebeenobservedbeensimultaneouslywithX-rayspikes.AnalysisofsimultaneousIRandX-raylightcurveshasprovedthatclassCarescanbereconstructedassumingacounterpartIRmicro-aresforeachoneoftheX-rayspikes Rothsteinetal. ( 2005 ).Atthispoint,wehavelaidthefoundationsfortherestofthescienticcomponentofthiswork.WehaveestablishedtheuniquenessofthemicroquasarGRS1915+105,aswellasitsconditionasideallaboratoryforthestudyoftheejectioneventsinmicroquasars.Wehavealsodemonstratedtheaccretion-ejection,X-ray-IR,andQPO-jetrelations.Inchapters 3 and 4 weanalyzeX-rayandIRobservationsofGRS1915+105tofurtherourunderstandingontheaccretion-ejectionprocessesinthismicroquasar.. 32

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Eikenberryetal. 2008 )conrmsthattheQPOisassociatedwithjetactivity,highlightingtheimportanceoftheanalysisofthisepochfortheunderstandingoftheaccretion-ejectionconnection.WecalculatethefractionalQPORMSvaluesatdifferentenergybands.ThehighQPOsignal-to-noiselevelsinourobservationsallowtherstpublishedmeasurementofQPORMSvaluesusingHEXTEdata.WendthatthespectralenergydistributionoftheQPOstronglyindicatesanorigininthehardnon-thermalemissioncomponent,suggestingasecondspectralcomponenttothehardnon-thermalX-rayemission.GiventheassociationoftheQPOswiththeobservedjetactivityinGRS1915+105,wesuggestthatthisadditionalnon-thermalX-rayspectralcomponentisdirectlylinkedtotherelativisticjetformationprocess. Castro-Tiradoetal. 1994 ),andlaterconrmedastherst-knownGalacticsuperluminaljetsource( Mirabel&Rodriguez 1994 ).Subsequentstudiesofthemicroquasarhave 33

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Mirabel&Rodrguez 1999 ).Inparticular,theX-rayemissionhasbeenclassiedinto12separateclassesbasedontheX-raycolorandcountrateoftheobservations( Bellonietal. 2000 ).SimultaneousobservationsofGRS1915+105atdifferentwavelengthsshowevidenceofadisk-jetcoupling( Eikenberryetal. 1998a ; Mirabeletal. 1998 ; Fender&Pooley 1998a ),basedonrepeatedX-rayactivity(boththermalandnon-thermal)associatedwithlong-wavelength(infraredandradio)ares.Diverseobservationsconrmthepresenceofaquasi-continuousradiosynchrotron-emittingrelativisticjetoutowduringX-ray/radioplateaustates( Klein-Woltetal. 2002 ).Low-frequencyX-rayQPOswerealsoseenintheprecedingwork,andseemtobeconsistentlylinkedtothepresenceofjets( Varniereetal. 2007 ). Eikenberryetal. ( 2008 )foundfastIRickering(timescalesof25s)apparentlyarisinginthebaseofthejet-formingregion,aswellasastrongX-rayQPO(1s)occurringsimultaneouslyduringthesameX-ray/radioplateauepochthatweanalyzeinthischapter.AlthoughX-rayQPOsinGRS1915+105havebeenknownalmostsincethediscoveryofthemicroquasar( Pauletal. 1997 ),thephysicaloriginoftheQPOsisstillunderdebate.X-rayQPOswereinitiallyconsideredasinstabilitiesintheinneraccretiondisk( Mirabel&Rodriguez 1994 ; Bellonietal. 1997 ),simplybasedonthefactthatQPOamplitudesareeasiertodetectattheenergiesatwhichtheblackbodyemissionisproducedintheaccretiondisk(2-10keV).SomemodelsexplainingtheLFQPOs(1-30Hz)inmicroquasarsstillrelatetheQPOfrequencywithafrequencyassociatedtotheinneraccretiondisk:e.g.,magnetoacousticalfrequency( Titarchuk&Fiorito 2004 )orKeplerianfrequency( Trudolyubovetal. 1999 ).PreviousstudieshavelargelyavoidedthestudyoftheX-rayLFQPOsathighenergies(15-100keV)becauseofthegreaterstrengthoftheQPOsatlowenergies(2-15keV),andhencestudieswerelimitedinmostcasestoenergiesbelow20keV.TheexactoriginoftheLFQPOsinGRS1915+105remainsunclear,withinitialworksuggestinganorigininthesoft/thermal 34

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Markwardtetal. 1999 ),butlaterworkinsteadindicatingahardernon-blackbodyorigin( Miklesetal. 2006 ).ThestudyofthefractionalQPORMSspectrahasshownsubsequentlythattheenergydependenceoftheQPORMSvaluesisharderthantheblackbodyemission( Zdziarskietal. 2005 ; Sobolewska&Zycki 2006 ; Rodriguezetal. 2008 ).ThehardQPORMSspectradecouplestheQPOsfromtheblackbodyemission,leavingthehardX-ray(E>10keV)astheenergyrangefromwhichtheQPOarises.TheconrmationofthehardspectraoftheQPOs,andthelinkbetweenQPOsandjetactivity( Varniereetal. 2007 ),bothduringX-rayplateauepochssimilartotheoneweanalyzeinthischapter,opennewpossibilitiesforthephysicaloriginoftheQPOs.WehaveuseddatafromboththeProportionalCounterArray(PCA)andtheHighEnergyX-rayTimingExperiment(HEXTE)instrumentsofRXTEtoanalyzetheX-rayemissionfromGRS1915+105.TodateveryfewstudieshavebeenconductedtoanalyzetheemissionfromGRS1915+105usingHEXTEdata,despiteHEXTEdatagenerallybeingavailablewheneverPCAdataisavailable.Sections 3.2 and 3.3 aredevotedtothedatareductionandtheclassicationofourobservations.InSection 3.4 ,wepresentanalysisoftheX-rayhigh-speedickering.Section 3.5 isfocusedontheanalysisofthespectraltting.Finally,inSection 3.6 wecalculatethefractionalQPORMSspectrainordertostudytheoriginoftheQPOs.WendevidencesuggestingthatthesourceofemissionoftheQPOisdifferentthanthatoftheblackbodyemissionorthepowerlawradiation,contradictingtheoriesthatplaceitsformationintheinnerpartoftheaccretiondiskorinthehotcorona,andsupportingtheconclusionsof Zdziarskietal. ( 2005 ); Sobolewska&Zycki ( 2006 ); Miklesetal. ( 2006 );and Rodriguezetal. ( 2008 )whichpointtoanon-thermaloriginfortheQPO.InthischapterweanalyzeevidencethatsupportsanewinterpretationoftheoriginoftheX-rayLFQPOsinGRS1915+105.Thisprojectispartofamulti-wavelengthstudyoftheGRS1915+105system(Eikenberryetal.2012inprep.)thatwillpresentafully 35

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3-1 ).Thetwoepochscorrespondtotwochronologicallyconsecutivebutphenomenologicallydifferentstatesofthemicroquasar.ObservationsduringEpoch1correspondtoatypicalhardstatewithQPOs:April16th(2observations)and23rd,2003;theotherthreeobservationscorrespondtohigh-variabilitysoftstates,Epoch2:June9th,19thand24th,2003.WeuseddatafromboththePCAandtheHEXTEinstrumentsonboardtheRossiX-rayTimingExplorer(RXTE).CoevalHST/NICMOSobservationsconrmthepresenceofrelativisticjetoutowsduringEpoch1,andtheabsenceofthejetduringEpoch2( Eikenberryetal. 2008 ).Wehavefollowedtheschemeof Bellonietal. ( 2000 )forclassifyingtheX-rayvariability.Weclassifyobservations1,2,and3asbelongingtoclass,observations4and5asclass,andobservation6asclass(Table 3-1 ).Wehavealsoanalyzedoverahundreddifferentadditionalclassobservationsfromotherobservationdates.AlthoughallofthemcontainaQPO,thesignaltonoiselevelsoftheQPOsintheHEXTEdatagenerallyaretoolowforasignicantanalysisofthefractionalQPORMSspectraathighenergies.Thoseobservationsincludethesetsofobservationsusedby Sobolewska&Zycki ( 2006 )and Rodriguezetal. ( 2008 )intheiranalysisoftheQPORMSvariability.Theseanalyses,restrictedtoPCAdata,arediscussedinSection 3.7 .OursetofobservationspresentssignaltonoiselevelsoftheQPOamplitudeatleasttwotimeshigherintheHEXTEenergybands15-20keVand20-25keVthaninthoseotherepochs,allowingustocalculate,forthersttime,theRMSvariabilityofQPOsinGRS1915+105usingHEXTEdata. 36

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Observationsummary Obs.ObsIDExp.DateMJDX-rayQPONo(sec)class 170702-01-50-003373Apr.16,200352745.1839Yes270702-01-50-012052Apr.16,200352745.2568Yes370702-01-51-002924Apr.23,200352752.2202Yes480701-01-05-006863Jun.09,200352799.0397No580701-01-06-004514Jun.19,200352809.0377No680701-01-07-001155Jun.24,200352814.9790No Bellonietal. ( 2000 )schemeasshowninSection 3.2 3-1 :leftandcentralpanels).ObservationstakenduringthehighX-ray/radioactivityepoch(Obs.4,5,and6)donotshowanytraceofaQPOatanyenergyband(Fig. 3-1 :rightpanels).InallEpoch1observations,the 37

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Miklesetal. 2006 ),thefrequencyoftheQPOsshowsnoevolutionwithtimeduringanyofthethreeobservationsofEpoch1.ThestablecentroidfrequencyexhibitedbytheQPOduringourobservationsfacilitatestheintegrationofthelongclasslightcurves,increasingthesignal-to-noiseleveloftheQPO,andallowingustoproduceananalysisoftheRMSvariability.Thisisakeyfactorinourstudy,especiallywhenusingHEXTEdatawherethemeannumberofcountsismuchlowerthaninthePCAdata. Munoetal. 1999 );andthe15-240keVHEXTEspectrumwithastandardmodelofahardpowerlawwiththesamehydrogencolumndensity.Theadditionofanironlinearound6keVwasnecessaryinobservations1,2,and3( Miller&Homan 2004 ).Inobservation4,5,and6anironlinearound6keVisalsoobservedintheresidualsofthettingbuttheimprovementtothe 38

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Leftpanels,fromtoptobottom:PCAdata,non-normalizedpowerspectrumfromobservations1,2,and3.Centralpanels,fromtoptobottom:HEXTEdata,non-normalizedpowerspectrumfromobservations1,2,and3.Astrong0.8HzQPOispresentatallenergiesbelow30keV.Theamplitudeofthe0.8HzQPOismaximumforthe5-8keVband,decreasingafterwardswithincreasingenergy,anddisappearingabove30keV.Rightpanels,fromtoptobottom:PCAdata,non-normalizedpowerspectrumfromobservations4,5,and6.NoQPOispresentatanyenergybands. tisstatisticallymarginalwhenaddingtheline.Thevaluesofreduced2forthettingofbothPCAandHEXTEspectraforoursixobservationsarealwayslowerthan1.37,showingagoodstatisticalt.Backgroundemissionstartstakingoverthepowerlawemissionaround80keVanddominatesaround100keV.ForthisreasonwelimittheanalysisoftheX-rayemissionfromthemicroquasartothe2to80keVenergyrange. 39

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3-2 .AsteeppowerlawispresentintheHEXTEobservationswithalmostconstantphotonindices(3.3)throughoutallobservations.FromtheseHEXTEphotonindicesweexpectsimilarconstantphotonindicesforthesixPCAobservations.However,thevaluesofthePCAphotonindicesaresignicantlylower(atter)inthethreeobservationswithoutQPOspresent(2.5),andareevenlowerinthethreeobservationswithQPOspresent(2.0).WhenttingthePCAspectrumusingtheparametersobtainedforthepurepowerlawspectrumoftheHEXTE-onlydata,thetsarepoor,andstatisticallyrejectable.Thisdiscrepancyinthepowerlawphotonindexseeninseveralsourceshasbeenassumedbysomeauthorstobeaninstrumentalcalibrationerror( Sobczaketal. 2000 ). Wilmsetal. ( 1999 )obtainavalueof0.134fortheinstrumentalcalibrationuncertaintyusingthePCAandHEXTEbesttphotonindicestotheCrabNebula.Whilesuchcalibrationuncertaintiesarecertainlypresentinourdata,theyareapproximately5to10timestoosmalltoexplainthediscrepancieswefoundhere.Instead,wesuggestthatthehigherdiscrepancyseeninthephotonindexesofobservationswithQPOsisanobservationalfactsupportingtheexistenceofasecondemissioncomponentcontributingtothepowerlawatenergieslowerthan30keV,alongwiththe(stronger)evidencefromtheQPORMSspectra(Section 3.6 ).Thechangeinthepowerlawindicescanbeexplainedassumingthatthenewcomponentisacut-offpowerlawlikecomponent.Thepresenceofacut-offpowerlawwillaccountforthehardeningofthephotonindices.Wefurthernotethat Rodriguezetal. ( 2008 )investigatetheQPORMSspectraandndthattheQPOisbest-ttedwithacut-offpowerlaw.Weperformedspectraltsincorporatingasecondhardpowerlawcomponent.Themodelsusedtotthespectrumincludeatypicalblackholemodelwiththeinclusionofacut-offpowerlaw(i.e.gaussian+blackbody+cut-offpowerlaw+powerlaw).Althoughstatisticallygoodtswerefoundtotheoveralluxspectrumineachcase,noneoftheindividualspectralcomponentstracktheQPOspectraverywell.Thecut-offpowerlaw 40

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SpectralFittingSummary.Obs:ObservationID.Tin:kTtemperatureatinnerdiskradius(keV).Norm bb:diskbbnormalizationfactor.PhoIndex:photonindexofpowerlaw.Norm pl:photonskeV1cm2s1at1keV.Red.2:reduced2. PCA Tin2.030.032.010.032.020.031.5190.0151.5360.0151.5020.013Norm bb36.34.834.65.133.74.6273.423.9267.723.8206.616.4PhoIndex1.980.052.010.051.940.052.550.032.490.032.510.03Norm pl4.80.75.20.74.20.631.12.728.92.617.31.7Red.21.2521.4101.3461.3171.0871.234 HEXTE PhoIndex3.310.013.290.013.280.013.260.013.220.012.960.03Norm pl172.77.9162.59.1154.97.8196.56.0198.66.849.14.3Red.21.3701.0141.3061.2261.1731.108 Sobolewska&Zycki ( 2006 )(gaussian+blackbody+thcomp+thcomp)and Rodriguezetal. ( 2008 )(gaussian+comptt+powerlaw).WefoundthatthesoftComptonizationcomponentof Sobolewska&Zycki ( 2006 )modeldoesnotttheQPOathighenergies,whilethecompttcomponentof Rodriguezetal. ( 2008 )failstotthelowenergiesoftheQPOspectrum.Theimprovementinthereduced2ismarginalinallcasescomparedwiththatobtainedusingthestandardsoftblackbodyplussinglehardpowerlawmodel.DespiteourinabilitytondacommonlyusedmodelthattstheQPOspectraovertheentirerangeofenergies,wediscussinSection 3.7 alltheevidencesupportingtheexistenceofsuchaQPOcomponent. 3.4 ,thepoweroftheQPOatdifferentenergybandsfollowsthesameroughtrendastheuxofthesource;thepowerpeaksatthesameenergies 41

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3 ).ThefractionalRMSvaluesgiveusameasureoftheproportionofthetotalenergyemittedthatisbeingusedtogeneratetheQPO,i.e.,providesuswithameasureofthepercentageofthetotalenergyateachenergybandthatcontributestotheQPO.ThereforetheRMSvaluesareameasurementthatdoesnotdependdirectlyonthetotalux.Wecalculatethenon-normalizedpowerspectrumon32s-longlightcurvesegments.ThefractionalQPORMSvaluesareobtainedusingEqs. 3 .WedeterminethebackgroundamplitudeintherangeoffrequenciesoftheQPObyttingthemeannon-normalizedpowerspectrumtoaquadraticexpressionintherangeoffrequenciesfrom0.5Hzto1.5Hz,excludingthefrequenciesoftheQPO. Pqpo(E)=Non-normalizedpoweroftheQPOateachenergyband 42

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FractionalQPORMSamplitudeatthedifferentenergybandsforobservations1,2,and3,fromtoptobottomrespectively.ThefractionalRMSspectraincreaseswithenergyinthesoftX-rays,getstoamaximumandisapproximatelyconstantbetween10and25keV,correspondingtothemaximumemissionofthehardX-rays,anddecreasesafterwardsremainingverylowandconstantabove30keV.Forcomparison,valuesoffractionalRMSforbothinstrumentsareshownintheenergybandD(15-20keV).SeeAppendix 9 forerrorbarcalculations. 43

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3-2 ).ForthepurposeofcomparingPCAandHEXTEinstrumentswehaveplottedthevaluesofRMSamplitudeintheenergybandD(15-20keV)fordatafrombothinstruments.WehavecombinedthethreefractionalRMScurvesintoonesinglecurveforbetterstatisticalanalysis(Fig. 3-3 ).ComparingtheRMScurvewiththedifferentcomponentsofthemicroquasaremission,wendthatthefractionalRMSvaluesarelowintherangeofenergieswheretheblackbodyemissionismaximum(2to5keV);increaseswithenergyintherangeofenergieswheretheblackbodyemissiondecreases(5to15keV);andismaximumwherethepowerlawemissiondominates(15-25keV).WeconcludefromthoseresultsthatblackbodyemissionprovidesasmallercontributiontotheQPOsthanthepowerlawemission;andtherefore,despitethelowerstrengthoftheQPOathigherenergies,thehighervaluesofthefractionalRMSintherangeofhardX-rayenergies,wherethepowerlawradiationdominatesovertheblackbodyradiation,implyacommonsourceofemissionfortheQPOsandthepowerlawradiation.OncewehaveestablishedacommonoriginfortheQPOsandthepowerlaw,weexaminethedrop-offofthefractionalRMSvaluesatenergiesabove30keV.Tothatend,inFig. 3-3 wehaveoverplottedthenormalizedfractionaluxofboththeblackbodyandpowerlawemissionextractedwiththeXSPECpackage.Above18keVtheemissionisexclusivelypowerlawradiation.AssumingtheQPOhasacommonoriginwiththepowerlawradiation,thevalueoftheexpectedRMSspectrashouldremainconstantandmaximumabove18keV.Instead,themeasuredRMSvaluesdecreaseabove25keVandareminimumabove30keV.ThediscrepancybetweenthemeasuredRMSvaluesoftheenergybandG(30-80keV)andtheexpectedmaximumRMSvaluesis2.86.Thisindicatesthatthedrop-offoftheRMSspectraisnotaneffectofthecalculationerrors.The2testgivesavalueof8.46whenappliedbetweenthemeasuredRMSvalues(HEXTEvaluesonly)andtheexpectedspectra(powerlawfractionalux).Thus,weconcludethatthedecreaseintheRMSspectraisarealeffectinthedata.Thiseffect 44

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CombinationofthethreefractionalQPORMSspectracurveswith1errorbarsoverplotted.Alsoplottedarethenormalizedfractionaluxfortheblackbodyandpowerlawemission.Thediscrepancybetweenthenormalizedfractionalux(expectedRMSspectra)ofthepowerlawandthemeasuredfractionalRMSvalueintheenergybandG(30-80keV)isjustbelow3.0(seeSection 3.6 ). canbeexplainediftherearetworatherthanonepowerlawcomponents,thesofteronebeingacut-offpowerlawaccountingfortheQPO.ThecombinationoftheresultsobtainedfromthePCA/HEXTEphotonindexdiscrepancy(Section 3.5 )andfromtheRMSspectracurveleadsustoproposeanewmodeloftheemissionofGRS1915+105comprisedofasoftmulti-temperaturediskblackbodycomponentplustwopowerlawcomponents.Thesecondcomponentofthepowerlawemissionwouldhaveashorterdetectablerangeofenergythantheoverallpowerlawemission,E<30keV;andwouldhaveacommonoriginwiththeLFQPO. 45

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Bellonietal. ( 2000 )scheme.InoureffortstounveiltheoriginoftheX-rayLFQPOsinGRS1915+105,wehaveusedthesamefractionalRMSmethodappliedby Zdziarskietal. ( 2005 ); Sobolewska&Zycki ( 2006 ); Rodriguezetal. ( 2008 )tointerprettheemissionfromthemicroquasar.WendthatthefractionalamplitudeoftheuxcontributingtotheQPOcontinuestobehighatenergiesbeyondwhichtheaccretiondiskblackbodyemission(withT2keV)isnegligible,andinfactreachesitspeakatenergiesof15-20keVbeforedecliningsharplyandbecomingnon-detectableatE>30keV.ThisclearlyindicatesthattheQPOphenomenonismuchmorestronglylinkedtothehardpowerlawemissionfromGRS1915+105thanitistothesoftthermalblackbodyemissioninfact,theenergydependenceoftheQPOfractionalamplitudeisconsistentwithzeroQPOcontributionfromthethermalcomponent(i.e.apurenon-blackbodyorigin).ThecombinationofthefractionalRMSmethodwithanalysisoftheX-rayspectrumrevealsreasonableevidencetoproposeanewmodelofthehardX-rayemissionofthemicroquasarGRS1915+105,incorporatingacut-offpowerlawcomponentinadditiontothetraditionalmodelcomprisedofthecombinationofonesoftmulti-temperaturediskblackbodyplusonehardpowerlaw.TheprimaryevidenceforthissecondhardX-raypowerlawcomponentcomesfromthefactthattheenergydependenceofthe1.2sQPOwhileclearlyharderthanthethermalcomponentissignicantlysofterthantheoveralldependenceofthehardX-rayuxfromGRS1915+105intheHEXTEbandpass.Infact,thisQPOcut-offpowerlawcomponentessentiallydisappearsatenergiesabove30keV,whilethehardX-rayuxcontinues.Asecondarypieceofevidencecomesfromthestatistically-signicantdifferenceinpowerlawindicesderivedfromthePCAandHEXTEbandpasses.Previousauthorshaveinvestigatedthisdiscrepancyandhaveascribedthedifferencetolarger-than-expectedcalibrationerrorsbetweenthePCAandHEXTEinstruments.Thelargediscrepanciespresentinourobservations,5to10timeslargerthanthecalibrationerrorsmeasuredby Wilmsetal. ( 1999 )intheCrab 46

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Varniereetal. 2007 ),andthatmanymodelsofjetformationpredictnon-thermalX-raypowerlawemissionarisingfromthejet-producingregion( Markoffetal. 2005 ),themostobviousexplanationisthatthisspectralcomponentarisesinthejet-producingregioninGRS1915+105.Inthatcase,thenwehave,forthersttime,identiedX-rayemissionarisingdirectlyfromthejet-producingregioninGRS1915+105.AmoredetailedstudyofthispossibilityisanalyzedinEikenberryetal.2012(inprep),wherethisnewmodeloftheX-rayemissionisincorporatedwithinamulti-wavelengthmodeloftheemissionofGRS1915+105.Fig. 3-4 showsarepresentationofthestandardandLasso-Cabreraetal.modeloftheX-rayemissionofGRS1915+105.OurtheoryofathirdcomponentinthemodelofemissionofGRS1915+105arisingfromthejet-producingregionissupportedbythepresenceofcoevalickeringon 47

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Standard(left)andLasso-Cabreraetal.(right)modelsoftheX-rayemissionofGRS1915+105.IntheLasso-Cabreraetal.modeltheoriginoftheQPOislocatedinthejet-formingregion. timescalesof25sintheIRsynchrotronemission( Eikenberryetal. 2008 ).ThehighfrequencyoscillationintheIRemissionprovidesthebasisforconsideringanoscillatingjetwhichcouldbelinkedtotheoscillationfoundintheX-rayemission.TheinclusionoftheQPOcut-offpowerlawarisingfromthebaseofthejetintheX-raymodelofGRS1915+105complementsthetheoryofanIRoscillatingjetbutatdistancesmuchshorter,i.e.inthejetformingregionitself.AlthoughinthischapterwehaveonlyanalyzedtheQPOcut-offpowerlawcomponentduringclassobservations,wethinksuchacomponentisnotlimitedtothisclassofobservations. Miklesetal. ( 2006 ),usingclassobservations,foundastrongcorrelationbetweentheQPOandbothcomponentsofamodelcomprisedofamulti-temperatureblackbodyplusahardpowerlaw.TheyshowthatthecorrelationoftheQPOwiththepowerlawcomponentisstrongerthanwiththeblackbodycomponent,althoughitweakenssignicantlyinsomeepochs.Wethinktheoccasionalweakeningoftheoverallcorrelationwouldbeduetodecouplingbetweenourproposedthirdcomponentandtheaccretiondisk/corona.TheyalsoshowthatthecorrelationoftheQPOwitheitherthepowerlawuxortheblackbodytemperatureisweakerwhenthe 48

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ModelsoftheX-rayemissionofGRS1915+105. ComponentStandardSobolewskaRodriguezLasso-CabreraModelZycki(2006)etal.(2008)etal. SoftBBAccret.DiskAccret.Disk-Accret.DiskHardPLHotCorona-JetHotCoronaQPOPL---JetSofCompt.-Cooling/HeatHotCorona-HardCompt.-HotCorona-partialcontributionoftheotherisremoved.Suchadecreaseinthecorrelationcouldbeexplainedbythepresenceofathirdspectralcomponent,i.e.theQPOcut-offpowerlaw,whichhasitspeakofemissioninenergiesabovethepeakoftheblackbodyandbelowthepeakofemissionofthepowerlaw.So,thehiddenthirdcomponentwillbedividedbetweentheothertwocomponentsoftheemissioninthettingprocess,decreasingtheobservedcorrelationoftheQPOwithonecomponentwhentheothercomponentincludingpartoftheQPOcut-offpowerlawiseliminated.RMSvariabilityanalysissuchastheonepresentedinthischapterarelimitedinclassobservationsbytheshortdurationofthedipsandtheevolutionofthecentroidfrequencyalongthedip( Miklesetal. 2006 ).Thus,thesignaltonoiseleveloftheQPOistoolowtoperformouranalysis,especiallyinthecaseoftheHEXTEdata.PreviousauthorshavealsodetectedtheatteningoftheRMSspectra( Zdziarskietal. 2005 )orthebeginningoftheturnoverintheQPOspectrumaround20keV( Sobolewska&Zycki 2006 ; Rodriguezetal. 2008 )usingQPORMSindifferentsetsofclassobservations.TheirstudieswerelimitedinbothcasesbytheuseofonlyPCAdata.WeanalyzedallthepreviousobservationsandfoundthattheQPOsignaltonoiselevelsintheHEXTEenergybandsaretoolowtoperformaQPORMSanalysis.OurworkheresolidiesthediscoveryoftheturnoverintheQPOspectrumbyaddingtothestudytheuseofHEXTEdata,andweproposeacompletelydifferentexplanationfortheoriginoftheQPO. Zdziarskietal. ( 2005 ),detectingonlytheatteningoftheQPORMSspectrabutnotobservingtheturnover,concludedthattheQPORMSvalues 49

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Sobolewska&Zycki ( 2006 )proposedamodelcomprisedofablackbodycomponentplustwothermalComptonizedcomponents.TheysuggestthatthesofterofthethermalComptonizedcomponentsaccountsfortheQPOspectrumbymeansofmodulationofthecooling/heatingrates.However,theyalsondthatnoneoftheirproposedcomponentsexactlytrackedtheQPOspectrum. Rodriguezetal. ( 2008 )proposedamodeloftheemissionofGRS1915+105composedofaComptonizedcomponentplusahardpowerlawlinkedwiththeemissionofthejet.Theyfoundnowell-matchedcontributiontothespectrumoftheQPOfromeitherofthosetwocomponents,andproposedtheLFQPOstobemorecompatiblewithmodelsofdiskinstabilities.Incontrast,webelieveourwork,supportedbythestrongcorrelationbetweentheQPOandthehardpowerlaw( Miklesetal. 2006 )andespeciallybythepresenceofsimultaneous25sIRjetickering( Eikenberryetal. 2008 ),laysasolidfoundationforplacingtheoriginoftheQPOinthejet-producingregion,andthereforeforproposingathirdcomponentinthemodelofemissionofthemicroquasarGRS1915+105withitsorigininthejet-producingregion.Table 3-3 showsacomparisonbetweenthedifferentmodelsoftheX-rayemission.Thisidenticationwillbeparticularlyimportantfortheoreticalmodelsofrelativisticjetproductionaroundblackholes.Forinstance,theAccretionEjectionInstability(AEI)modelforjetproduction( Varniereetal. 2007 )hasrecentlybeenshowntomatchcorrelationsbetweentheinneraccretiondiskradiusandQPOfrequency( Miklesetal. 2009 ).However,theAEImodeldependsonalarge-scaleglobaloscillationproducingtheQPOatlargediskradii.Thus,theassociationofthejetproducingregionwithnon-thermalX-rayemissionextendinguptoE30keVwillprovideimportantconstraintsformodelssuchasthisinfuturework. 50

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51

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Castro-Tiradoetal. 1994 ),andlaterrevealeditselfasthemostvariablemicroquasarinthesky.TheGRS1915+105systemcontainsoneofthemostmassiveGalacticstellarmassblackholes14Mknowntodate( Harlaftis&Greiner 2004 ),andpresentsanextremelyhighaccretionrate,whichislikelytoaccountforthehighvariabilityobservedintheradio,infrared(IR),andX-rayemissionofthisobject.Duringthe20-yearlifespanofthecurrentoutburststate,GRS1915+105hasexhibitedhighly-variableX-rayemissionthathasbeenclassiedin12differentclassesdependingoncountratesandcolor-colordiagram( Bellonietal. 2000 ),threetypesofdifferentIRaresclassesA,B,andCdependingonthedurationandtheuxdensitystrength( Eikenberry 2001 ),andpresenceofsuperluminalradioejections( Mirabel&Rodriguez 1994 ).Simultaneousmulti-wavelengthobservationsofGRS1915+105haveprovedtheinterconnectionbetweenallthosephenomena,showingevidenceofadisk-jetcoupling( Eikenberryetal. 1998a ; Mirabeletal. 1998 ; Fender&Pooley 1998b ; Rothsteinetal. 2005 ).Inparticular, Eikenberryetal. ( 1998a )and Rothsteinetal. ( 2005 )showclearevidenceoftheconnectionbetweentheX-rayemittinginneraccretiondiskandtheIRcompactjetwiththeobservationofseveralcyclesofsimultaneousIRaresandhighX-rayvariability. Eikenberryetal. ( 1998a )presentrepeatedepisodesofsimultaneoussynchrotronproducedclassBIRares(100mJy)andclassX-rayvariabilityastherst-everobservationalevidenceoftheinteractionbetweentheinnerdiskandtherelativisticcompactjetinablackholesystem(Fig. 4-1 ).TheyassumeasynchrotronoriginoftheIRemission( Fenderetal. 1997 ; Pooley&Fender 1997 ),withadiabaticexpansionasthedominantcoolingmechanism( Mirabeletal. 1998 ),andruleoutthermalreprocessingoftheX-rayuxontheouterdiskand/orthecompanionstarastheoriginoftheIRaresbecauseofthedecouplingoftheX-rayandIRexcessesatlatetimesinsomeoftheares.Theyexplainthoseepisodesassumingascenarioof 52

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Eikenberryetal. ( 2000 )explainsthelowIRexcessobservedafterthedecouplingofthe Eikenberryetal. ( 1998a )IRandX-rayaresandbeforethereturntothequiescentvaluebyassociatingeachX-rayoscillationwithasmall(5-10mJy)IRsubare. Rothsteinetal. ( 2005 )usethissameideatoexplaintheIRaresobservedinasimilarscenarioofrepeatedepisodesofsimultaneousclassCIRares(40mJy)and,inthiscase,classX-rayvariability,whichisalsopresentedasevidenceofjetformationinGRS1915+105(Fig. 4-2 ).TheyassociateeachX-rayoscillationtoasimulated8mJygaussiansubarewithvariableFWHM,obtainingasimulatedoverallIRarecomposedofthesuperpositionoffaintsubaresthatresemblestheoriginallightcurve.TheyconsidertheseIRaresofthesametypeastheonesobservedby Eikenberryetal. ( 2000 )andthereforealsoassumeasynchrotronoriginforthem.WeinterpretthisresultsasanscenariowherethejetoutowsareformedbyplasmoidblobslaunchedfromtheaccretiondiskandickeringintheIRmicroares.ThefrequencyoftheickeringofthemicroaresgivesusanupperlimitofthediameteroftheblobsandthedelaybetweentheX-rayandIRisanindicationofthedistancebetweentheoriginoftheX-rayandtheoriginoftheIRemission.However,inthissecondsetofobservations,thedurationoftheIRandX-rayaresarealwayssimilar,leavingopenthepossibilityforthermalreprocessingastheoriginoftheIRares.Inbothscenariosobservedby Eikenberryetal. ( 1998a )and Rothsteinetal. ( 2005 ),theIRandX-rayexcessesseemtobetriggeredbyaninitialX-rayspike.Moreover,thedelaysbetweenthistriggerspikeandthepeaksoftheIRandX-rayuxesareconstantwithineachscenarioindicatingapossiblecommontriggerfortheIRandX-rayaresineachcase,thusaccentuatingthesimilaritiesbetweenthosetwosetsofobservationsdespitehavingdifferenttypeofX-rayvariability.Thestudyofsimultaneousdifferentenergyrangelightcurvesfrommicroquasarsiscurrentlythemostpromisingsourceofinformationtoextendourknowledgeofthe 53

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Gandhietal. 2008 2010 ; Durantetal. 2011 ),SWIFTJ1753.5-0127( Durantetal. 2008 2011 ),ScoX-1( Durantetal. 2011 ),andCygX-2( Durantetal. 2011 ),whichwereobservedintheoptical(VLT/ULTRACAM)andX-ray(RXTE/PCA)wavelengthalwaysduringthelow/hardstateofthemicroquasars.TheCCFtechniquerevealslagsbetweentheopticalandtheX-rayemissioninallthoseobjects,withtheopticalleadingtheX-ray,thatcannotbeexplainedbytheexpectedreprocessingoftheX-rayradiationintheopticallythickouterdiskand/orthesurfaceofthecompanionstar.Thisimpliesanewsourceofopticalemissionneverconsideredbeforeinmicroquasarmodels.However,CCFstudiesinvolvingIRandX-rayradiationofmicroquasarswerelimiteduntilnowtothemicroquasarGX339-4. Casellaetal. ( 2010 )presentasubsecondtimeresolutionCCFstudyoftheIR(VLT/ISAAC)andX-ray(RXTE/PCA)emissionofGX339-4duringthehighlyvariablelow/hardstate.TheyobserveastrongcorrelationbetweentheIRandtheX-rayemission,withtheIRlaggingtheX-rayby100ms,thusconstrainingtheLorentzfactorofthejetto>2andthejetspeedtomildlyrelativisticneartheformingregion.InthecaseofGRS1915+105,thehighextinctiontowarditslocationintheGalacticPlanereducesitsbrightnesstoK-band 54

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Eikenberryetal. ( 1998a )and Rothsteinetal. ( 2005 ).WealsousetheresultsoftheCCFtocomparesimulatedIRlightcurveswiththerealones.ThesimulatedIRlightcurvesprovideevidenceofickeringIRemissionwithquasi-periodicfrequenciesintherange0.1to0.3HzsimultaneouslywiththeX-rayclassepoch.Ourresultsareconsistentwiththepreviouslyobserved25sIRvariabilityinGRS1915+105( Eikenberryetal. 2008 )inthattheyconrmthepresenceofahighlyvariableIRrelativisticjetanddismissestheideaofreprocessingasthesourceofemissionoftheIRradiationintheobservationsof Rothsteinetal. ( 2005 ). Eikenberryetal. ( 1998a )and Rothsteinetal. ( 2005 ),respectively.Forbrevity'ssake,weprovideanabbreviatedsummaryhereandreferthereadertothosearticlesformoredetailsaboutthedatareduction.IRobservationswereobtainedusingthePalomar200-inchtelescopeandtheCassegrainD-78near-IRcameraintheK(2.2m)band,withX-rayobservationsobtainedusingtheProportionalCounterArray(PCA)on-boardtheRossiX-rayTimingExplorer(RXTE).The1998IRdatawereobtainedwith0.1stimeresolutionandrebinneddownto1sinpost-processing,andthe2002IRdataandtheX-rayobservationswereobtainedwith1stimeresolution.AbsolutetimingfortheIRobservationswasprovidedbyaWWVBreceiverwith1msaccuracy.IRuxesarecalibratedusingthenearbyStarA(K=13.3mag),andinthecaseofthe2002observationsdereddenedbyAK=3.3magtocompensateforthehighGalacticplaneabsorption( Fenderetal. 1997 ).ToconrmtheclassicationoftheX-rayobservations,wehavereducedtheoriginalPCARXTEdataandhavefollowedtheschemeof Bellonietal. ( 2000 )forclassifyingtheX-rayvariability.Weagreewith Rothsteinetal. ( 2005 )in 55

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OriginalsimultaneousX-rayandIRobservationson1997August14(leftcolumn)and15(rightcolumn)at1stimeresolution.ShownherearetheportionsofthelightcurveswheresimultaneousclassBIRaresandhighclassX-rayvariabilityperiodsarepresent.ReprintedbypermissionfromEikenberry,Stephen.1998. Eikenberryetal. ( 1998a ). OriginalsimultaneousX-rayanddereddenedIRobservationson2002July27(upperpanel)and28(lowerpanel)at1stimeresolution.SeveralClassBIRaresaresimultaneouswithhighclassX-rayvariabilityperiods.ReprintedbypermissionfromRothstein,David.2005. Rothsteinetal. ( 2005 ). 56

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4-1 showsonlytheportionofthe1997lightcurveswheresimultaneousclassBIRaresandhighX-rayclassvariabilityarepresent( Eikenberryetal. 1998a ),andFig. 4-2 showsthe2002lightcurveswiththeIRuxdereddenedtocompensatetheGalacticplaneabsorption( Rothsteinetal. 2005 ).Forcomparison,uxdensityonthe1997observationscanbedereddenedmultiplyingbyafactorof100.4AK,withAKequalto3.3mag( Fenderetal. 1997 ).Ineachepoch,weindividuallyanalyzealltheportionsofthelightcurvesthatcontainsimultaneouscoverageoftheX-raylow/hardstateperiods,i.e.,theX-raydips,andoftheX-rayhigh-variabilitystateperiods,i.e.,theares.Wedividealltheperiodsin60sbinsandcalculatetheCCFineachbin.ForourcomparisonofthelowhardplateaustatewecalculatethemeanCCFofallconsecutive60sbinscoveringeachentirelongdippresentintheclassesandobservations.Whilethistechniqueisvalidfortheplateaustatewheretherearenovisualfeaturesasreferences,itisnotvalidforthehigh-variabilityperiodsbecauseofthepresenceoftheX-rayspikes.ThevariableperiodicityoftheX-rayspikeswouldcausethespiketobeinadifferentpositionineachbin,therefore,wecalculatethemeanCCFusing60sbinscenteredonlyontheX-rayspikesthatpresentawelldenedvisualpeak.Thisapproximationgivesusareferenceforthecenterofthebinsthatfacilitatesthecomparisonbetweenallbins,althoughitcausessomelossoftemporalinformationwhendismissingthelesswell-denedpeaks.WealsoinvestigatetherelativeevolutionofthetwosignalsrepresentingtheindividualCCFsofall60sbinsversustimeforthelow/hardstate 57

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MeanCCFofeachoftheclass(leftcolumn)andclass(rightcolumn)low/hardstateperiodsshowninFig. 4-6 .Nocorrelationisfoundinanyofthelow/hardstates. epochs,andversusthepeakpositionwherepeaknumber1istherstnarrowpeakforthehigh-variabilityepochs. 4-3 showsthemeanCCFoftheclassandclasslow/hardstateperiods.ThemeanCCFplotsoftheclasslow/hardstateperiodspresentastrongcorrelationwithalmostzero 58

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MeanCCFofeachofthe1997August14(leftcolumn)and15(rightcolumn)highclassX-rayactivityperiodsshowninFig. 4-7 .Althoughwithsimilarshape,thelagofthecorrelationvariesfromperiodtoperiod,i.e.,avariablecorrelation. lagthat,asweshowinSection 4.5 ,areclearlydominatedbytherstthree60sbins.ItisstraightforwardtoseetheresemblancebetweenthemeanCCFoftheclassesandperiodsincaseofeliminationofthestrongcorrelationbins.Theseresultssuggestthatthephysicalprocesseshappeningbetweenthecompactjetandtheaccretiondiskduringthelow/hardstatesoftheX-rayclassesandobservationshaveasimilarbehaviorwithlittleornointeraction.Figs. 4-4 and 4-5 showthemeanCCFoftheclassandclasshighX-rayvariabilityperiods.ThemeanCCFplotsofthehigh-variabilityperiodsaresimilarwithin 59

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MeanCCFofeachofthe2002July27highclassX-rayactivityperiodsshowninFig. 4-7 .Asimilarstrongcorrelationispresentinallperiods. eachvariabilitytypealthoughcompletelydifferentbetweenthem.Inotherwords,theclasshigh-variabilityepochsallresembleeachother,andtheclasshigh-variabilityepochsallresembleeachother,buttheclassCCFsaredifferentformtheclassCCFs.ThemeanCCFsoftheclasshigh-variabilityperiodsshowasimilarpatternofcorrelationsandanti-correlationsinallperiodsalthoughwithvariablelags,i.e.,avariablecorrelation.ConsideringthatwehaveplacedtheX-raypeaksasareferenceinthecenterofthe60slightcurvesandthatallX-raypeakswithinthesamevariabilitytypehaveacommonorigin,theclassmeanCCFplotssuggestthattheIRuxhaveacommonbehaviorwithsomekindoforganizationinallperiodsalthoughwith 60

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Rothsteinetal. ( 2005 ). 4-6 ).WeobserveasmallevolutionoftheCCFduringthelow/hardstateoftheX-rayclassobservationswithastrongcorrelationintherst3bins(180s)atapproximately 61

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Evolutionofthe60sCCFsduringthe1997August14class(leftcolumn)and2002July27class(rightcolumn)low/hardstateperiods.Clearevidenceofanevolutionarypatternisseenintheclassperiods,withastrongcorrelationatthebeginningoftheperiodthatdisappearswithtime.Despitebeinginasimilarstate,theclassobservationsdonotshowsuchanevolutionarypattern. zerolagthatfadeswithtime.SincethecorrelationishappeningwhentheX-rayandIRuxesarestilldecreasingandbeforetheyreachtheminimumvalues,webelievethisstrongcorrelationcouldbecontaminationduetoaremnantoftheprevioushighX-rayvariabilitystate.Thethreebinscorrespondtoapproximately25%oftheanalyzedlightcurvesandwillrequiredfurtherinvestigation.SuchevolutionisnotobservedduringthecomparablestateintheclassobservationsdespiteshowingasimilarrandombehavioroftheCCFatlatertimes.Ifwedismissthosethreebinsoftheclassobservations,bothclassesandlow/hardstatesshownointerconnectionbetweentheX-rayandIRlightcurves.Unlikethelow/hardstateperiods,thehighX-rayvariabilityperiodsshownoCCFresemblancebetweentheclassesandobservationsatanytime.Fig. 4-7 showstheevolutionoftheCCFwithinthehighX-rayvariabilityperiodsofbothepochs.Theclass 62

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Evolutionofthe60sCCFscenteredontheX-raypeaksduringtheclass(August14:threeupperpanelsofleftcolumn;August15:threelowerpanelsofleftcolumn),andclass(rightcolumn)highX-rayactivityperiods.Noevolutionarypatternisobservedinanyoftheplots,althoughtheclassCCFsshowhighertendencyforanti-correlationsatnegativelagsthanatpositivelags. 63

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4-8 and 4-9 showthenormalized60sX-rayandsimulatedIRlightcurves(leftcolumns)andtheX-raytorealandsimulatedCCF(rightcolumns)forsomeoftheclassesandhighX-rayvariabilitypeaks,respectively.TheKStestindicatesthattheprobabilityofthetwoCCFbeingsimilarforeachpeakisalwayshigherthan1andinsomecasesbeyondthe2levelofcondence(Table 4-1 ).Despitehavinghighprobabilitiesthese 64

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KStestandMonteCarlosimulationresultsfortheclassesandhighX-rayvariabilitypeaksshowninFigs. 4-8 & 4-9 PeakKStestMonteCarlo(%)(%) Aug14-278.377.9Aug14-378.370.8Aug14-691.052.2Aug14-778.378.9Jul27-298.080.6Jul27-398.081.4Jul27-491.050.1Jul27-778.370.1 resultsarenotstatisticallyconclusivebythemselvestoconrmthesimulatedlightcurvesassignicants.TodeterminetherealstatisticalsignicanceofthesimulatedIRlightcurvesweperformaMonteCarlosimulationofthesimulatedIRlightcurvesusingthesamegroupofgaussiansineachcasebutallowingrandomvaluesofthecenterofthegaussians.Weperform1000realizationsforeach60sbinandfoundthatfortheclasspeaks<10%exceedthemanualCCFKSvalues,andthatfortheclasspeaksthatnumbergoesdownto<1%.Table 4-1 showstheresultsoftheMonteCarlosimulations.TheMonteCarlosimulationindicatesthattheprobabilityofhavingKStestvaluesequalorhigherthantheoneobtainedwiththesimulatedlightcurveswhentheindividualgaussiansarerandomlydistributedisaround2fortheindividualclasspeaksandaround3levelofstatisticalsignicancefortheindividualclasspeaks.Therefore,assumingallgaussiansubareswithineachepochoriginatefromthesamephenomenon,theoverallsignicanceofthesimulatedlightcurvesduringclassesand,consideringonlythefourexamplesofeachclasspresentedhere,become4and6,respectively.Fromtheseresults,weconcludethatthesimulatedIRlightcurvesthatwehavecreatedtoreproducetheIRemissionofGRS1915+105duringthe1997X-rayclassandthe2002X-rayclassperiodsarestatisticallysignicant,indicatingthepresenceofaickeringIRemissioninGRS1915+105duringbothhighX-rayvariabilityepochs. 65

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NormalizedrealX-rayandsimulatedIRlightcurves(leftcolumn),andrealandsimulatedCCFs(rightcolumn)forthepeaknumbers2,3,6,and7oftheclassrstperiod(topleftpanelinFig. 4-7 ). AnanalysisofthesimulatedIRlightcurvesshowthatwhiletheclassIRlightcurvesarecomposedofagroupofindependentpeaksnotassociatedwiththeX-rayemission,theclasssimulatedIRlightcurvesarecomposedofquasi-periodicgaussiansubareswithsteadyfrequencieswithineach60speriodandvaryingamongperiods 66

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NormalizedrealX-rayandsimulatedIRlightcurves(leftcolumn),andrealandsimulatedCCFs(rightcolumn)forthepeaknumbers2,3,4,and7oftheclassrstperiod(toprightpanelinFig. 4-7 ). intherange0.1to0.3Hz(Table 4-2 ),i.e.,between3and8timesfasterthananypreviouslyobservedIRvariabilityinGRS1915+105( Eikenberryetal. 2008 ).Moreover,theclasssimulatedIRlightcurvesshow,inmostcases,incrementsinstrengthaftertheX-raypeaks.TheratioofthetotalIRnormalizeduxatpositivelagsversusthe 67

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ParametersoftheIRsimulatedlightcurves:meanfrequencyoftheIRickering;ratiooftheoveralluxatpositivelagsrespecttheoveralluxatnegativelagsfortheclasshighX-rayvariabilitypeaksshownin 4-9 ;lagbetweentheX-raypeakandthecentroidoftheIRexcess;andlagbetweenthebeginningoftheX-rayriseandtherstIRsubareoftheexcess. PeakPeriodPost/NegLagFluxIRPeakLagIRRiseLag(s)(%)(s)(s) Jul27-271+24117Jul27-361-413Jul27-462+671512Jul27-752+451913 totalIRnormalizeduxatnegativelagsvariesbetween20%and70%(Table 4-2 ).ThestrengtheningoftheIRickeringaftertheX-raypeakindicatesaninterconnectionbetweentheX-rayandIRuxes,i.e.,betweenthephysicalprocesseshappeninginthehotinneraccretiondiskandtheIRemission.Theseresultsconrmtheexistenceofquasi-periodicoscillationsintheIRemissionofGRS1915+105duringtheclassCIRaressimultaneouswithX-rayclassvariability.ApossibleexplanationfortheoriginoftheIRemissioncouldbereprocessingoftheX-rayemissionintheouterdiskand/orcompanionstar.WebelievethatthepresenceofverynarrowfeaturesintheIRemissionofGRS1915+105isinconsistentwithreprocessingoftheX-ray.ReprocessingblurstheX-raysignaltolongeraIRsignal,whileweseetheoppositeherewiththepresenceofthenarrowfeatures.Also,althoughthefastmodulation(0.1-0.3Hz)observedinthesimulatedIRlightcurvescouldbeexplainedasreprocessingoftheX-rayinafastspinningouterdiskorcompanionstar,itwouldbehard,ifnotimpossible,toexplainthechangeonthemodulationfrequencyoftheIRvariabilityfromX-raypeaktoX-raypeakonperiodsshorterthan100s,i.e.,muchfasterthantheorbitaltimescalesfortheouterdiskorcompanionstar.Hence,thepresenceofickeringIRemissionrelatedwiththeX-rayemissiondismissestheideaofreprocessingoftheX-rayuxintheouterdiskand/orcompanionstarastheoriginoftheIR,andstrengthentheideaofaickeringsynchrotronemittingIRjet. 68

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Rothsteinetal. 2005 ),itisstraightforwardtoassumethatthe2002overallclassCIRaressimultaneouswithX-rayclassvariabilityalsohaveanoriginintheoutowevents.Asimilarassumptionismoredifculttoapplytothe1997classBIRaressimultaneouswithX-rayclassbecauseofthelackofcorrelationbetweenthesimulatedIRlightcurvesandtheX-rayemission.However, Eikenberryetal. ( 1998a ),forthosesameobservations,probethejetoriginoftheares.Consequently,theclassBandCaresanalyzedherehaveasimilarorigininarelativisticIRjet.Nevertheless,thesimulatedIRlightcurvesshownoresemblancebetweenepochs,suggestingdifferentnatureofthejetformationinthesetwoepochs.Theclasssimulatedsignalsindicateawell-organizedjetwheretheickeringpresentsaquasi-steadyrepetitionandwithastrongcoherencewiththeprocesseshappeningintheX-rayemission,typicalofajetstronglycorrelatedwiththeaccretionprocesses.Meanwhile,theclasssimulatedsignalsshowanunorganizedjetformedbystochasticprocesseswithnocoherencewiththeX-rayemission,moretypicalofanoisyformationprocess.OncewehaveestablishedtheoriginoftheIRemissioninasynchrotron-emittingrelativisticjetoutow,weusethesimulatedIRlightcurvesoftheclasshigh-variabilityepochtoanalyzethephysicalprocesseshappeningbetweentheaccretiondiskandthejet.RadioobservationsofGRS1915+105duringalow/hardstateplacetheoriginoftheradiosynchrotronemissionatadistanceof50AUfromtheaccretiondisk( Klein-Woltetal. 2002 ; Dhawanetal. 2000 ). Eikenberryetal. ( 2008 ),assumingconservationof 69

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Eikenberryetal. 2008 ),wecanplacethesourceofproductionoftheIRickeringlocatedbetween0.3and0.8AUfromthecompactobject,andwithadiameteroftheplasmoidblobsbetween0.006and0.016AU.However,thesimulatedIRlightcurvesalsoshowameantimelagbetweentheX-raypeakandthecentroidoftheIRexcessof14sandameantimelagbetweenthebeginningoftheX-rayriseandthebeginningoftherstsubareoftheIRexcessof10s(Table 4-2 ).Adelayof10sbetweentheX-rayandIRemissionindicatesamaximumdistancebetweentheaccretiondiskandtheIRlaunchsiteof0.02AU,i.e.,50timesshorterthanexpectedfromtheIRickering.Theshortdistanceofthelaunchsiteandthelowerlimitof0.006AUforthediameteroftheplasmoidblobsobtainedfromthe3sickeringindicatethatweareobservingphysicalphenomenaproducedveryclosetotheoriginoftheIRplasmoidejection.Fig. 4-10 showsarepresentationofthejetdistancesanddiameters.WehavedemonstratedthatbothmeasurementsofthetimelagsbetweentheX-rayandIRemissionindicateanunambiguoustimedelaybetweentheX-rayemissionandtheplasmoidejectionsincontradictiontothehypothesisofanoutside-inprocesspresentedby Eikenberryetal. ( 2000 ).Also,thedistanceobtainedfortheoriginoftheIRemissionis15timesshorterthantheaccretiondiskouterradiusofGRS1915+1050.3AU( Rauetal. 2003 ),denitelyconrmingtheinconsistencyofourresultswiththereprocessingintheouterdiskand/orcompanionstarasoriginoftheIRemission.Reprocessingcouldstillbepossibleinalumpintheinnerdisk,althoughthepresenceofthenarrowIRpulsescontradictsthatexplanation. 70

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Diagramofthejetdistancesandplasmablobdiametersatscale. OursimulatedIRlightcurvespresentvariationswithfrequenciesintherange0.1to0.3Hzthatcannotbedetectedintheoriginallightcurves.Thepowerspectrumofthe60soriginalIRlightcurvesshowthepresenceofweakquasi-periodicoscillations(QPOs)atthesamefrequenciesthanthesimulatedlightcurvesbutwithaverylowstatisticalsignicance.Althoughourresultsconrmtheinteractionbetweentheaccretiondiskandthejetinatleastoneofthevariabilitytypes,thehighX-rayvariabilityportionoftheclass,theyalsoshowthatthetimeresolution1saswellastheIRS/N10and25forthe1997and2002observations,respectivelyoftheobservationsanalyzedhere,andespeciallyofthehigh-variabilityperiods,areinsufcienttoproduceasignicantanalysisofthereallightcurvesandtounderstandthephysicalprocesshappeningbetweentheX-rayemittingaccretiondiskandtheIRejectionevents.DespitetheevidencepresentedhereofnoapparentIRtoX-raycorrelationduringtheclasshigh 71

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Eikenberryetal. ( 2008 )andaredifculttoexplainasreprocessingoftheX-rayemissionintheouterpartoftheaccretiondiskand/orcompanionstar.WeproposeinsteadthattheoriginoftheIRemissionisasynchrotron-emittingcompactjet,consistentwithseveralpreviousauthors( Fenderetal. 1997 ; Pooley&Fender 1997 ; Mirabeletal. 1998 ; Eikenberryetal. 1998a ; Rothstein 72

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, 2005 ).ThedelaybetweentheX-rayandIRlightcurvesindicatesalocationoftheIRlaunchsiteveryclosetothecompactobjectat<0.02AU.AlthoughthesimulatedlightcurvesclearlyindicatesadelaybetweentheX-rayandIRuxes,anaccurateestimationofthetimedelaycannotbeobtainedfromthemandwillhavetowaituntilhighertimeresolutionobservationsareavailable.Thefollowinginstrumentalpartofthisworkisfocusedonthedevelopmentofanear-IRastronomicalinstrument,theCanariasInfraRedCameraExperiment(CIRCE),thatwillallowustocaptureobservationsofGRS1915+105withatimeresolutionandS/Nlevelsneverachievebefore.WeexpecttouseCIRCEinthefuturetoconrmtheresultsofaickeringjetintheIRemissionofGRS1915+105presentedhere. 73

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6 ,wepresentacombinationoftwoSPIEproceedings( LassoCabreraetal. 2008 ; LassoCabreraetal. 2010 )dedicatedtothedescriptionoftheoriginalreadoutelectronicsdesign,andthedevelopmentandsignicanceofthefastphotometrymode.CIRCEwasinitiallydesignedtousea2048x2048HAWAII-2HgCdTearrayfromtheRockwellScienceCenter,incombinationwithin-housedesignedreadoutelectronics.Half-waythroughthecompletionofthisdissertationtheHAWAII-2HgCdTewasdiscontinued,forcingtheGeminiObservatorytheproviderofthesciencearrayforCIRCEtoprovideCIRCEwiththemoremodern2048x2048HAWAII-2RGarrayfromTeledyneScientic&Imaging.Thenewsciencearraywasincompatiblewiththeoriginalreadoutelectronics;thus,replacementreadoutelectronicsdevelopedincollaborationwiththeInter-UniversityCentreforAstronomyandAstrophysicsiscurrentlybeingtested.Chapter 7 describesthenalreadoutelectronicsdesignusedinCIRCE,aswellasthe 74

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8 ,wepresenttheresultoftheanalysisoftheimagequalitytestsperformedontheCIRCEopticalsystem.Wepresentedtheseresultsduringtherecent2012SPIEconference(Lassoetal.2012). Edwardsetal. 2004 2006 2008 ; Marn-Franchetal. 2006 ; Charcos-Llorensetal. 2008 ; LassoCabreraetal. 2008 2010 )1.SeeFig. 5-1 fordetailedtechnicalspecicationsandobservingmodesofCIRCE.Wheninitiallydesigned,CIRCEwasintendedtoprovidenear-IRimagingandspectroscopy

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CIRCEtechnicalspecicationsandobservingmodes. 76

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CIRCEOpticalLayout. capabilitieswiththeGTCuntilthearrivaloftheEspectrografoMultiobjetoInfraRojo(EMIR).TheimproveddesignofCIRCE,particularlytheadditionofpolarimetryandfastphotometrycapabilities,willcomplementthecapabilitiesofEMIR,ensuringthefunctionalityofCIRCEbeyondthearrivalofEMIR.CIRCEwillbetheonlynear-IRinstrumentattheGTCwithpolarimetryandfastphotometrycapabilities. 77

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5-2 showstheopticallayoutofCIRCE.Figs. 5-3 & 5-4 showthelocationoftheopticalcomponentswithinthedesignoftheinstrument.Toassureaminimumlevelofbackgroundnoisefromtheinstrument,thetemperatureofthesystemismaintainedat77Kusingliquidnitrogencooling. 78

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CIRCEOpticalBench. CIRCEOpticalBenchCurrentState.PhotocourtesyofLassoCabrera,NestorM. 79

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CIRCEDewardesignrearview. CIRCEDewarmountedonthecart.PhotocourtesyofLassoCabrera,NestorM. 80

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5-3 & 5-4 showtheopticalbenchwiththemirrors,lterbox,andnitrogentanks.Fig. 5-5 & 5-6 showthedesignandcurrentstateofthedewarrespectively. 5-2 & 5-3 ).Itslocationiscrucialtothecorrectfunctioningofthewholesystem.Atthepupil,theparallelraysfromdifferenteldpointscross,thereforeanyopticalelementplacedatthislocationwillintroduceanidenticallightlossinallpointsoftheimage,reducingthetotalthroughputofthesystembuteliminatingthecontributiontosystematicnoiseintheateld.Thelterbox,incombinationwiththefocalplanemechanism(Subsection 5.1.2.2 ),willempowertheobservertoswitchltersand/orobservingmodesinstantlyduringthenight.Awellplannedobservingrunwillallowtheobservertoaccommodateseveraldifferentcongurationsduringasinglenight,withoutopeningtheinstrument.Manufacturedinourmachineshop,thelterboxismadeentirelyofthesameAl-6061aluminumasthebenchandmirror,reducingthecontractiondifferenceswiththerestofthesystematworkingtemperatures.Thelterboxiscomposedof3lterwheels,onegrismwheel,andoneLyotwheel.Thelterandgrismwheelswillaccommodate4opticalelementseach.TheelectronicscomponentsthatallowthemovementofthedifferentwheelsaredescribedinChapter 7 .Figs. 5-7 & 5-8 showthelterboxdesign. 81

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CIRCEFilterBox. CIRCEFilterBoxImage.PhotocourtesyofLassoCabrera,NestorM. 82

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CIRCEFocalPlaneMechanismplacedinsidethetestdewarandreadyforthecryogenictesting.PhotocourtesyofLassoCabrera,NestorM. 7 .Fig. 5-9 showsthecurrentstateofthefocalplanemechanism.AlthoughmissingtheHWPmechanism,wehavestartedcryogenictestingofthein-outstage. 83

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2.5 ).ThehighextinctionatvisiblewavelengthstowardtheobjectI23.4mag,R>26mag( Boeeretal. 1996 )limitstheobservationofthecompanionstartoIRwavelengths. Mirabel&Rodriguez ( 1994 )obtainedtherstinfraredobservationofGRS1915+105usingthe2.2-mESO/IRAC2.TheyunveiledtheIRcounterpartofthesystem,aswellas,placedlimitsontheIRbandmagnitudes,J16mag,H15.5mag,andK13.5mag. Chatyetal. ( 1996 )observedthecounterpartintheJ,H,andKbandswiththe 85

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Bandyopadhyayetal. ( 1998 )observedanIRmodulationintheK-bandontheorderof30-40daysinamulti-wavelengthstudyusingK-bandobservationsfromthe1.8-mPerkins/OSIRIS. Neiletal. ( 2007 )present7yearsofK-bandmonitoringofGRS1915+105usingthe1.0-mYale/ANDICAMandthe1.3-mCTIO/ANDICAM.TheyconrmedthattheIRuxcontainsacomponentcorrelatedwiththeX-rayux,andthereforeassociatedwiththedisk,plusnonthermalIRaresnon-correlatedwithX-rayux.Theyalsoobservedathirdcontributionfromthecompanionstar,fromwhichtheyobtainedaPorb=30.80.2days.ClassAandBaresfromGRS1915+105havebeenobservedmultipletimesinradiowavelengths,e.g.,usingVLA( Mirabel&Rodriguez 1994 ; Rodriguez&Mirabel 1998 )orMERLIN( Fenderetal. 1998 ).However,theyarelimitedtothreeclassAandveclassBobservationsintheIRwavelengths. Mirabel&Rodrguez ( 1996 )usingthe3.8-mUKIRT,observedtherstclassAIRaresimultaneouslywitharadio-emittingoutow. Samsetal. ( 1996 )usingthe3.58-mNTT/SHARPobservedtheonlyevidenceofaresolvedIRjetattheradiolocationtodate. Eikenberryetal. ( 1997 )usedK-bandobservationswiththe2.1-mtelescopeatKittPeakNationalObservatorytofollowuptheresolvedIRjetobservedby Samsetal. ( 1996 ).Theyfoundnoevidenceoftheextendedemission,provingthelinkbetweentheIRoutowsandtheradio-emittingjets. Araietal. ( 2009 )observedaclassAareintheHandKbandusingthe1.5-mKANATA/TRISPEC. Fenderetal. ( 1997 )usingthe3.8-mUKIRT/IRCAM3,observedclassBIRaresintheK-band.Theyobservedevidenceforinfraredsynchrotronemission. Eikenberryetal. ( 1998a )usingthe5-mHaletelescope,observedclassBIRaresintheK-bandduringaclassX-rayepoch. Mirabeletal. ( 1998 )and Fender&Pooley ( 1998a )observedclassBIRaressimultaneouslywitharadio-emittingoutows,usingthe3.8-mUKIRT/IRCAM3andthe4.2-mWHT/WHIRCAM,respectively.ClassCaresofGRS1915+105arelimitedtoaveryfewIRobservations. Eikenberry 86

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( 2000 )and Rothsteinetal. ( 2005 )usingthe5-mHaletelescope,observedclassCIRaresassociatedwithshortX-raysoftdipsandwithaclassX-rayepochrespectively. Rothsteinetal. ( 2005 )discoveredseveralsporadicIRmicroareshappeningsimultaneouslywithX-rayuxpeaks.AssumingthenthateveryX-raypeakhasanIRcounterpart,theywereabletosimulatethewholeIRare.Thistechniquewasalsoappliedtotheclassaresobservedby Eikenberryetal. ( 1998a )withdifferentresults. Fuchsetal. ( 2003 )observedsimultaneouslyresolvedradiojet,brightnear-IRemission(possibleclassCare),andX-rayQPO,usingthe3.58-mNTT/SOFI. Uedaetal. ( 2006 )usingthe8.2-mSubaru/CISCOobservedclassCIRaresduringthedipsofanX-rayclass.OnsetoftheIRaresshowsadelaybetween0-3minuteswithrespecttothebeginningofthedips.Besidethoseground-basedobservations,theonlyIRspace-basedobservationofGRS1915+105wasmadeby Eikenberryetal. ( 2008 )usingtheHST/NICMOS.Theyfoundinfraredvariabilityof20-30%withatimescaleof25sduringaX-rayclassstate. Castro-Tiradoetal. ( 1996 )madetherstspectroscopicobservationsofGRS1915+105usingthe3.8-mUKIRT.TheyclaimedthatGRS1915+105waslikelyaLMXB. Eikenberryetal. ( 1998b )usingthe5-mHale/HNAstudiedtheH-I,He-I,andHe-IIlines.Theyfoundthelinesarisefromtheaccretiondisk,andthattheareemissionoriginatesfromejectamovingoutoftheaccretiondisk. Greineretal. ( 2001 )usingthe8.2-mVLT/ISAACidentiedthedonorstarasaK-MIIIstarwith1-1.5M,andclassiedGRS1915+105asaLMXB. Harlaftis&Greiner ( 2004 )usingalsothe8.2-mVLT/ISAAC,identiedthedonorstarasK-typegiantstarwithM=0.810.53M. Shahbazetal. ( 2008 )usedthe3.8-mUKIRT/UISTtoobtainHandKspectrafromGRS1915+105. 87

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Samsetal. ( 1996 )measuredthetotalpolarizationofthesystemusingthe3.58-mNTT/SHARP.Theyobtainedavalueofthepolarizationof2.70.6%.Thetotalnear-IRemissionisnotintrinsicallyhighlypolarized,andisconsistentwiththepolarizationduetomagneticorientationofinterstellardustgrainsintheGalacticPlane.Theyalsocalculatedanupperlimitforthejetpolarizationof30%,basedonthehighextinctionoftheIRwavelengths. Shahbazetal. ( 2008 )obtainedasimilarresultforthepolarizationofGRS1915+105.Theyusedthe3.8-mUKIRT/IRPOL2,andmeasuredatotalpolarizationof5.0%1.2%,alsoconsistentwithinterstellarpolarization. 88

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Eikenberryetal. ( 1997 )and Rothsteinetal. ( 2005 ).The Eikenberryetal. ( 1997 )observationsyieldS/Nvaluesof10whenusingthe5-mHaleTelescopewithtimeresolutionof0.1s,andlaterrebinnedto1s.The Rothsteinetal. ( 2005 )observations,withthesametelescopeandatimeresolutionof1s,yieldS/Nvaluesof25.Finally,S/Nlevelsinthe25saresobservedwithHST/NICMOSby Eikenberryetal. ( 2008 )arebetween12and100.Becauseoftherelevanceofthesearesforthiswork,wespecicallycalculatetheimprovementintimeresolutionandS/NlevelthatCIRCEwillprovideforsimilarares.WithK-bandmagnitudeof12.6andseeingof0.5arcsec,CIRCE'sS/NcalculatorgivesS/Nlevelsof175foratimeresolutionof0.1s,i.e.,GTC/CIRCEwillalmostdoublethebestS/NofHST/NICMOSwith80timeshighertimeresolution.Clearly,GTC/CIRCES/Nlevelswillsignicantlyimproveonanypreviousobservation,allowinghigherprecisionphotometric,polarimetricandspectroscopicstudies.ThehighS/NlevelsobtainedwiththeGTC/CIRCEwillallowforthersttimereliablephotometry,polarimetry,andspectroscopywithatimeresolutionlowerthan1s. 89

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4 .WeexpectthisobservationtoprovidedenitiveproofofthephysicaloriginoftheX-rayQPOs,allowingustoplacetheX-rayQPOswithinthecontextofthemicroquasaremissionmodel. 90

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Edwardsetal. 2008 ; Charcos-Llorensetal. 2008 ; LassoCabreraetal. 2008 2010 )( Elston 1998 ; Elstonetal. 2003 ; Eikenberryetal. 2004 ).BasedonthosesystemsweexpecttheinitialCIRCEelectronicstobeassuccessfulasitspredecessors.WediscussherethedifferentsubsystemsoftheinitialdesignofCIRCE'sreadoutelectronics. 91

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3 & 4 .Thebeginningofthischapterisdedicatedtothedescriptionofthebasicsubsystemsthatwereusedtocontroltheoriginalreadoutelectronicsoftheinstrument.TheinitialdesignofCIRCEreadoutelectronicswascreatedbyourformerelectricalengineerKevinHanna.MycontributiontothesystemwasbybuildingtheBiasandPreampBoards,aswellas,testingtheirfunctionality.TheremainderpartofthechapterisdevotedtotheworkIhavedoneonthedevelopmentoftheFastPhotometryMode. 6.1.1ArrayControllerSubsystem(MCE-3)DrivingandacquiringtheanalogdatafromtheRockwell2048x2048HgCdTeHAWAII-2arrayinthedewarrequiresapowerfulexternalcontroller.TheMCE-3(ModularCameraElectronicsver.#3)performsthosefunctionsfromwithinitsownthermalenclosure.Designedbasedonitspredecessors,andresidinginacustomVMEchassislocatedintheArraySignalProcessor(ASP),thefourmajorhardwarecomponentsassociatedwiththeASPare:thePatternGeneratorBoard(PGB),theMicroprocessorboard,theADCboard(s),andtheFiberInterfaceboard.APerleSerialTerminalServermoduleisusedtocontroltheArrayController(MCE-3),asitdoesinitspredecessors.Aberopticcableisusedastheseriallinktomaintainisolationfromtheremainderofthesystemandtelescope.ThesciencedataoutputfromtheMCE-3is 93

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6-1 .Thisboardperformstwomaintasks.TherstmaintaskistogenerateontheanalogsideoftheboardalltheClocklevelsandDClevelsrequiredforthereadoutoftheHAWAII-2array.ThesecondmaintaskofthisboardistoprotectthedetectorfromnoisecausedbytheTTLLevelControlLines.Thistaskisperformedbyopticallyisolatingthedetectorfromthoselines. 6-2 .Thelowerleftsectioncorrespondstotheclockingsection,andthelowerrightsectioncorrespondstotheDCanalogbiassection.DCandclockinggroundsareconnected.Finally,theuppersectioncorrespondstotheentrypointforallthedigitalsignals.Theopto-isolatorsarelocatedbridgingthatgapatthebottomofthedigitalsection. 94

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Left:PreampBoard.Right:BiasBoard.PhotocourtesyofLassoCabrera,NestorM. 95

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BiasBoarddigital/analogisolation.PhotocourtesyofLassoCabrera,NestorM. lines,areremoved.ThoseplugswilleliminateanyESDeventfromdirectcontactwiththeassociatedconnectorpins.Consideringthis,itisnotrecommendedthattheBiasenclosurebeopened,andtheBiasBoardbedisconnectedinanattempttoplaceashortingplugdirectlyonthedewarcaseconnector.Evenwiththesetwotypesofprotectionbuiltinprotectionandexternalprotection(plugs)usersmusttakecaretopracticenormalESDpreventiontechniqueswhenhandlingsensitivepartsoftheinstrument. 6-1 .ThePreampBoardisdesignedtobeatwostagepreampwithDCoffsetavailableforeachamplier.BothstagesaredesignedusingOPA627.DCoffsetsarenormallycontrolledbytheMCE-3rmware,althoughanenhancedcapabilityofthisboardallowscommandoftheDCoffsetsbyhighlevelsoftware.ThePreampBoard'smaintaskistodrive,bymeansoftheampliers,theanalogcablethatwillconnectthedetectorwiththeMCE-3ADCconverters.Thegainofthis 96

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Finger&Beletic ( 2003 ).WehavesuccessfullytestedthiscircuitintheFLAMINGOS-2systemandithasprovidedthenecessaryclockedgetoedgestability.Sinceitsintroduction,wehaveseennoclockinganomaliesthataretraceablebacktotheclock-1/clock-2edges. 97

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6-3 showsadiagramofthearraywiththequadrants,subquadrants,andreadingspeedanddirections.The2048x2048HAWAII-2arraycanbeconguredinanyofitsthreeoutputsmodesdependingontheuser'sneeds.ThosemodesareselectedbymeanofthedigitalcontrolssignalO1andO2. 98

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HAWAII-2readoutorganizationandeffectivereadoutareausingtheFastPhotometrymode. TheinformationrequiredtoreadthedetectoriscontainedinoneofthefunctionsofthermwarecalledCYCLETYPES(CT).Eachoneofthesefunctionsaretextlistsdeningtheactivitiestoperform.ThebasicCTusedtoreadthedetectorcongurestheHAWAII-2detectorintheeightoutputunshufedmode,andproducesthefollowingsequenceofsignals: 1. FSYNC:pulsedonceperframe,synchronizesthereadoutofeachframe(1/frame). 2. LSYNC:pulsedsometimebeforetherstpixelofeachrow,synchronizesthereadoutofeachrow(1/rowand1024/frame). 3. VCLK:pulsedtoincreasetheverticalshiftregister,synchronizesthechangeofrow(1/rowand1024/frame). 4. READ:allowsthereadoutofeachpixeloftherow(128/rowand131072/frame) 99

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6.2 formoredetails. 6-4 showsthebasiccomponentsofthereadoutelectronics.Thecurrentdesignoftheelectronicsoftheinstrumentcompromisesthereadoutspeedinordertoguaranteelowreadnoisewhenthedetectorisintheeightoutputunshufedmode.TherequirementsforthesignaltonoiseratioforCIRCElimitthepixelrateofthe32outputsofthearraytoamaximumof82Kpix/sinthestandardoperationmode.The32outputscomingoutofthedetectoraredriventothePreampBoard,wheretheyarerstmultiplexedto16channelsandthenamplied.Inordertokeepthepixeltransferrateequalattheentranceandtheexitoftheboard,multiplexingfrom32channelsto16channelsrequiresanincrementoftwointhepixeltransferspeedperchannel(164Kpix/s).The16outputsarethendividedinfourgroupsof4channels,eachonecorrespondingtoawholequadrant,andsenttofourdifferentADCBoardsresidingintheMCE-3.TheADCBoardslteranddigitalizetheanalogsignals,andmultiplextoonechanneleachgroupoffour.Thetransferspeedneedstobeincreasedbyfour(0.65Mpix/s).Thepixelsaredigitizedusingaconversionof32bitsperpixelsotheycanbetransmittedthroughthebackplaneoftheMCE-3.ThebackplaneoftheMCE-3transfersthesignalstotheFiberBoardthroughasingle32bitschannel,requiringagainanincrementinthetransferspeedperchanneloffour(2.6Mpix/s).The 100

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Diagramofthearrayreadout.Theredlabelsshowfundamentallimits.Inthestandardreadout,the32channelsofthedetectorarereadat82Kpix/s;multiplexedto16channelsandampliedinthePreampBoard;ltered,digitalized,andmultiplexedto4channelsintheADCBoards;transferredtotheFiberBoardthroughthebackplaneoftheMCE-3;andsenttotheObservatoryNetworkthroughtheFiberBoardanda2Gbber.Standardframerateis0.625Hz.

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6-4 ).Therstoneisimposedbythedetector.Thereadoutofthechannelsinthedetectorislimitedtoamaximumpixelsamplerateof140Kpix/s( Diazetal. 2004 ).Thelimitisimposedbythedetectoritselfandcannotbeexceeded.ThesecondfundamentallimitisimposedbythebackplaneoftheMCE-3.Thebackplaneiscontrolledusinga5MHzclock,with5/4overhead,limitingthepixelratehereto4Mpix/s.ThislimitcouldbeovercomeusingafasterclockbutwouldrequireconsiderablemodicationstothecurrentdesignofCIRCE. 6.2.1FastPhotometryAstronomicalinstrumentsaredesignedtocollectthemaximumamountofinformationinasingleobservation.Therefore,theirdesignsareingeneraloptimizedtoobservethemaximumeldofviewpossible.Tryingtoreachthelimitsforeachinstrument,detectorsarechosenwithmaximumsizepossiblewithoutnecessarilyconsideringthetotaltimeofframecapture.Thistrendinthedesignofinstrumentsisprobablyjustied,butwhenthegoalistoobservehighlyvariableobjects,thedesignchoicesforaninstrumentwillbedifferent.CIRCE,althoughdesignedbasedonthegeneralphilosophy,isgoingtobemodiedtoaccommodatethestudyofhighvariabilityobjects.Inmanycases,theobservedimageiscomposedoftheobjectofinterestplusmostlyuselessbackground.Often,mostofthisbackgroundcanberemovedwithoutcausinganyalterationtothestudyofthetarget.ThisisthephilosophyusedinCIRCEtodeveloptheFastPhotometrymode.Reductionoftheeffectivesizeofthedetector 102

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6.1.7 ,everynewreadingsequence/modeneedstheimplementationofanewCTinthermwareofthesystem.InthecaseoftheFastPhotometrymode,subarrayreadoutareimplementedmakingsimplemodicationsinthermware.AnewCTisrequiredtoperformFastPhotometry.ThisnewCTwillbeamodicationofthebasicCTusedtoperformtheEightOutput,Unshufedstandardmode(Subsection 6.1.7 ).TheREADsignalwillonlybeactivatedintherowstoread,remaininginactivefortheunusedrows,allowingreadoutsofanysubframesizepreviouslyselectedbytheobserver.ThenewCTwillonlyclocktheredundantrowsatafastrate,andwillclockandreadthedesiredpixelsonthedesiredrowsatamuchslowerrate.ThesequenceofsignalsforthecaseofeightoutputunshufedFastPhotometrymodeis: 1. FSYNC:pulsedonceperframe,synchronizesthereadoutofeachframe(1/frame). 2. LSYNC:pulsedsometimebeforetherstpixelofeachrow,synchronizesthereadoutofeachrow(1/rowand1024/frame). 3. VCLK:pulsedtoincreasetheverticalshiftregister,synchronizesthechangeofrow(1/rowand1024/frame). 4. Steps2and3arerepeatedasmanytimesasthenumberofredundantrows. 5. READ:allowsthereadoutofeachpixelofeachrowonlyinthedesiredrows(128/rowand((subframesize/2)*128)/frame).ThedesignoftheHAWAII-2arrayin32independentsubquadrantswithoneparalleloutputforeachone,willproduceaneffectivereadoutareaperquadrantof1024by(subframesize/2)pixels.Fig. 6-3 showstheeffectivesubframereadouts.Post-processingofthereaddatawilleliminateredundantpixels.TheFastPhotometrymodecanbealsoimplementedincombinationwiththeSingleOutputModeofthedetector.ThesequenceofsignalsforthecaseofsingleoutputmodeisthesamethatfortheeightoutputunshufedmodewiththedifferencethattheREADsignalispulsed(subframesize/2)/rowand(subframesize/2)2/frame. 103

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6-1 showsacomparisonbetweenthereadouttimesusingthisoptionfortheFastPhotometrymodewithdifferentsubframesizesversusthereadouttimeofthe2048x2048HAWAII-232outputsarray.ThesimplestoptionwillallowCIRCEtoreacha512x512pixelframerateof2.5Hz(Fig. 6-6 ),ora256x256pixelframerateof5Hz(Fig. 6-7 ).Thereadouttimeswithsubframesizesof512x512and256x256pixelsdecreaseto23%and13%ofthewholeframereadouttime.ExpectedreadouttimesarealsorepresentedinTable 6-1 .Assumingatypicalreadouttimeof1.5sforthe2048x2048HAWAII-232outputsarray,thereadouttimeofthe512x512and256x256HAWAII-2subarrayswouldbe0.39and0.195srespectively.Theonlymodicationneededisthecreationofanewcycletypeinthermwarethatwillclockthe1024-Nredundantrows,andwillclockandreadtheNdesiredrowsasexplainedinSubsection 6.2.1 .Therestoftheelectronicswillremainthesame.Thiscreatesastaggeredcrosspatternonthearray,includinga2Nx2N-pixelcontiguouscentral 104

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ExpectedreadouttimesusingtheFastPhotometrymodewithdifferentcongurationsoftheHAWAII-2array,comparedwiththereadouttimeoftheHAWAII-2with32outputs. DetectortypeFramesizeReadoutTimevsReadoutTime(pixels)2048HAWAII-2ReadoutTime(sec) HAWAII-2(32outputs)2048x2048100%1.5HAWAII-2(32outputs)1024x102450%0.75HAWAII-2(32outputs)512x51226%0.39HAWAII-2(32outputs)256x25613%0.195 squareeldofview(Fig. 6-3 ).Theredundantpixelsoutsidethecentralsquarewillbeeliminatedinpost-processingofthedata.WewouldliketoremarkherethatthisverysimpleoptionisgoingtobeappliedtotheMCE-4onFLAMINGOS-2becauseofitssimplicity.FLAMINGOS-2isaNear-Infraredwideeldimagerandmulti-objectspectrometerforuseonGemini-SouththathasbeenbuiltbyourteamontheUniversityofFlorida. 6-8 ).Asimplechangeintheelectronicswillreducethepixelrateinthebackplanebelowthefundamentallimit.ThemultiplexinginthePreampBoardcanbeskippedmodifyingthecurrentcodeoftheMotorola68020microprocessorthatcontrolstheMCE-3.Onlyhalfofthesubquadrantswillberead,reducingthepixelratebyhalf,andkeepingthecentralsquareframe.Thetechniquewilllimitourframetoamaximumof256x256pixelswithaframerateof8.5Hz(Fig. 6-9 ).Thisframerateof8.5Hzisthemaximumpossiblefora256x256pixelframewiththeHAWAII-2array.In 105

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HAWAII-2typicalframesizes.Bluesquaresrepresentthefollowingsubframesizes:2048x2048,512x512,256x256,and128x128pixel. additiontothemodicationsontheclockandthecodeofthemicroprocessor,anewCT,similartotheoneusedinoption1,hastobecreated. 106

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Comparisonoftheframerateforthedifferentoptionsandframesizes. DetectorsizeOriginalOption1Option2Option3Option4 2048x20480.625Hz----512x512-2.5Hz-2.13Hz4.3Hz256x256-5Hz8.5Hz8.5Hz8.5Hz inthismodemodifyingthecodeonthemicroprocessor.Thenewcongurationofthedetectorwillrequiresomechangesintheelectronics.ToaccommodatethedetectorinitsnewmodetothecurrentdesignoftheelectronicsofCIRCEthemultiplexingintheADCBoardsneedtobesuppressed.AsinthePreampBoard,themultiplexingintheADCBoardscanbeskippedbymodifyingthecodeofthemicroprocessor.InthiscongurationCIRCEwillbeabletoreacha512x512pixelframerateof2.13Hz(Fig. 6-10 )ora256x256pixelframerateof8.5Hz(Fig. 6-11 ). 6-12 ),anda256x256pixelframerateof8.5Hz(Fig. 6-13 ).ThesetwopixelframesarethemaximumpossibleforthoseframesizesandtheHAWAII-2array. 107

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6-2 showsacomparisonoftheframeratesforallfouroptionandtwodifferentsubframessizes. 108

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DiagramoftheOption1512x512subarrayreadoutusing32outputs.Atadetectorreadoutrateof82Kpix/snoneofthefundamentallimitsaffectsthereadout.512x512subarrayframerateis2.5Hz.

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DiagramoftheOption1256x256subarrayreadoutusing32outputs.Atadetectorreadoutrateof82Kpix/snoneofthefundamentallimitsaffectsthereadout.256x256subarrayframerateis5Hz.

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Diagramofa256x256subarrayreadoutusing32outputs.Atadetectorreadoutrateof140Kpix/s(fundamentallimitforthereadout)thebackplanefundamentallimitimpedesthereadoutofthedetector.

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DiagramoftheOption2256x256subarrayreadoutusing16outputs.Atadetectorreadoutrateof140Kpix/s(fundamentallimitforthereadout)theexceededfundamentallimitinthebackplaneoftheMCE-3(Fig. 6-8 )canbeavoidedwiththesuppressionofthemultiplexorsinthePreampBoard.256x256subarrayframerateis8.5Hz.

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DiagramoftheOption3512x512subarrayreadoutusing4outputs.Atadetectorreadoutrateof140Kpix/s(fundamentallimitforthereadout)theexceededfundamentallimitinthebackplaneoftheMCE-3(Fig. 6-8 )canbeavoidedwiththesuppressionofthemultiplexorsinthePreampBoardandtheADCBoards.512x512subarrayframerateis2.13Hz.

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DiagramoftheOption3256x256subarrayreadoutusing4outputs.Atadetectorreadoutrateof140Kpix/s(fundamentallimitforthereadout)theexceededfundamentallimitinthebackplaneoftheMCE-3(Fig. 6-8 )canbeavoidedwiththesuppressionofthemultiplexorsinthePreampBoardandADCBoards.256x256subarrayframerateis8.5Hz.

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DiagramoftheOption4512x512subarrayreadoutusing16outputs.Atadetectorreadoutrateof140Kpix/s(fundamentallimitforthereadout)theexceededfundamentallimitinthebackplaneoftheMCE-3(Fig. 6-8 )canbeavoidedrewiringthedetectoroutputstomultiplexorsconnections.512x512subarrayframerateis4.3Hz.

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DiagramoftheOption4256x256subarrayreadoutusing16outputs.Atadetectorreadoutrateof140Kpix/s(fundamentallimitforthereadout)theexceededfundamentallimitinthebackplaneoftheMCE-3(Fig. 6-8 )canbeavoidedrewiringthedetectoroutputstomultiplexorsconnections.256x256subarrayframerateis8.5Hz.

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5 ),andwehavedescribedtheinitiallyproposedreadoutelectronicsdesignforCIRCE(Chapter 6 ).Inthischapter,wearegoingtothoroughlydescribetheelectronicsdesignofCIRCE,includingthehousekeepingelectronics,theLogicControlUnit(LCU),andthenalreadoutelectronicsweareplanningtouseinCIRCE.Thedesignofanastronomicalinstrumentisaverycomplextaskthatinvolvescoordinationbetweenseveralengineeringelds:mechanics,optics,andelectronics.Generally,onlymechanicalandopticaldesignsareshownwhendescribinganinstrument,leavingasidetheelectronic.Despitebeingasrelevantfortheoperationoftheinstrumentasthemechanicalandopticaldesigns,electronicsdesignsareonlycommontoinstrumentbuildersandnottotheastronomicalcommunity.Liketheopticalandmechanicaldesigns,theelectronicsdesignofaninstrumenthastobeplannedinadvancetoguaranteeperfectfunctionalityandtointegratethedifferentelectricalpartswiththerestofthecomponentsofthesystem,i.e.,electricalcomponentshavetotwithinthemechanicaldesignwithoutinterferingwiththeopticalsystem.ThedesignofaninstrumentforinfraredobservationsoftheskyisamorecomplextaskthanwhendesigningforthevisibleregimebecauseIRwavelengthsareassociatedwithheatradiation.IRobservationrequireseliminationofanypossiblesourceofheatalongthelightpathtoreducebackgroundnoiseduetotheradiatedheat.Forthatreason,infraredastronomicalinstrumentsneedtobecooleddowntoatemperatureof77K,minimizingtheheatradiationfromtheinstrumentitselfandavoidingtheinteractionoftheinstrumentheatwiththesignalfromtheobservedobject.Asideeffectofsuchalowworkingtemperatureisthatthewatervaporintheaircouldcondenseonthemirrors 117

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118

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7.1 wepresentaglobalviewoftheelectronicdesignofCIRCEthroughthetoplevelanddewarcablemapsoftheinstrument.Inthefollowingsections,wedescribeindetaileachindividualcomponentoftheelectronicdesign.Section 7.2 describesalltheelectroniccomponentsrequiredtomaintaintheinstrumentoperatingattheworkingtemperatureandpressureaswellastheelectronicsofthedifferentmovingmechanismslocatedinsidethedewar.Section 7.3 isdedicatedtothedescriptionoftheLCUandthecommunicationsbetweenthecontrolcomputer(observercomputer)andthedifferentsystemsoftheinstrument.Finally,inSection 7.4 weintroducethenalsolutionweplantousetocontrol/readtheHawaii-2RGinfraredarray. 7.1.1 )andDewar(Subsec. 7.1.2 )cablemaps.Additionally,theremainingsectionsincludecablemapsofthedifferentelectronicsubsystemsofCIRCE.Asimportantastheyare,thecablemapsbythemselvesareinsufcienttobuildorthoroughlyunderstandtheelectronicsofanyinstrument.Moredetaileddocumentationcontainingspecicinformationforeachcomponentofthecablemapsisrequired.Althoughnotshownhere,wehavecreatedindividualdocuments,similartotheoneshowninFig. 7-1 ,foreachoneoftheCI-XXXXlabeledcablesofthecablemaps(Figs. 7-2 7-3 7-4 7-6 7-5 ,& 7-13 ).Thesedocumentscontainthespecications 119

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ExampleCIRCECableDocument. concerningeachindividualcable:cablenumber;functionality;numberofcontacts,typeofconnector,andtypeofmatingconnectorforeachsideofthecable;specialassemblynotes;anddetaileddescriptionsofeachcontactanditsfunctionality.Thesedocumentsareanessentialtoolforbuildingandguaranteeingproperfunctioningofthedifferentsystemsoftheinstrument. 7-2 )representsaglobalviewoftheinstrument,showingallthemaincomponentsoftheinstrumentaswellastheinterconnectionsbetweenthecomponents,andthecomponentsandthetelescopefacilities.Thecenter 120

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7-2 representthenaldesignsforthedewarandtheLCUrack,respectively,withtheleftsiderepresentingtheAnalogSignalProcessor(ASP)theoriginalreadoutelectronicsdescribedinChapter 6 .SincethenaldecisionabouttheintegrationoftheSIDECARASIC-IUCAAcardwithinourinstrumentispendingonthecryogenictestofthissystem(Sec. 7.4 ),nofurtherimprovementhasbeenmadetothetoplevelcablemaponthereadoutelectronicsside.Onceanaldecisionisreached,theASPrackwillbeeliminatedfromtheTopLevelCableMapbecausethereducedsizeoftheIUCAAcardwillfacilitateitsintegrationonthebackofthedewar,eliminatingtheneedfortheASPrack.Thetoplevelcablemaponlyshowstheelementsexternallyattachedtothedewar.Startingfromthetopandgoingcounterclockwise,thedewarhasthefollowingelementsattachedtoit:thewindowcover,whichprotectstheentrancewindowwhenevertheinstrumentisnotonthetelescope(Subsec. 7.2.2 );thePfeifferTPG261pressuregauge,whichmonitorsthedewarinternalpressure(Subsec. 7.2.1 );thebiasandpreampboards,whicharepartoftheoriginalreadoutelectronicsandwillberemovedinthenalcablemap;the15footlongCI-4201,CI-4202,CI-4203,andCI-9101cables,whichdriveallthehousekeepingsignalsinandoutthedewarthroughtheconnectorvacuumplate(Subsec. 7.2.3 );andthewarmupheaterbox,whichprovidesthepowertooperatetheheatersinsidethedewar,reducingthewarmuptimebeforetheinstrumentcanbeopenedifneeded(Subsec. 7.2 ).TherightsideofthetoplevelcablemapshowsalltheinterconnectionsbetweenthedifferentcomponentsoftheLCU.ThoseconnectionsareexplainedinmoredetailinSec. 7.3 .Theconnectionsbetweenthetelescopefacilitiesandtheinstrument(LCUrack)arelocatedinthebottomofthedrawingarea.Theinstrumentisalmostself-sufcient,onlyrequiringasourceofpowerandasourceofcoolingliquidusedtorefrigeratetheLCUrack.TwoindependentlynetworkconnectionsbetweentheLCUrackandthe 121

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CIRCECableMapTopLevel.

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7-3 )showsalltheelectroniccomponentsthatareplacedinsidethedewar.Allsignalsarrivethroughtheconnectorvacuumplate(Subsec. 7.2.3 )usinghermeticSeries-IIIandD-subconnectorstopassthroughthedewarandcoldshield,respectively.Hereagain,thelowerleftsidecablescomingintothedewartothedetectorbelongtotheoriginalreadoutelectronicsandwillbereplacedonceanaldecisionismadeonthenewreadoutelectronics.Insidethedewarthereareatotalof10temperaturesensors(Subsec. 7.2.1 ),6warmupheaters(Subsec. 7.2.1 ),and7motors(Subsec. 7.2.2 )externallymonitoredand/orcontrolledthroughtheLCUrack.Spreadthroughouttheopticalbench,8temperaturesensorsmonitorthetemperatureoftheinstrumentatalltimes.Theremainingtwotemperaturesensorsandoneoftheheatersarededicatedtothetemperaturecontrolofthemostdelicatecomponentoftheinstrument,theHawaii-2RGarray,becauseitsdesignrequiresaccuratecontroloverthewarmupprocessofthiscomponent.Theremainderoftheheatersareuniformlydistributedaroundthebenchtofacilitatetheprocessofwarmup.The7motorslocatedinsidethedewararedividedbetweenthelterbox(Subsecs. 5.1.2.1 & 7.2.2 )andthefocalplanemechanism(Subsecs. 5.1.2.2 & 7.2.2 ).Thelterboxcontains5motors,oneperwheel,whilethefocalplanemechanismcontainsonetranslationalandonerotationalmotor.Eachelementofthecablemapmotors,heaters,ortemperaturesensorscanbedisconnectedindependentlyoringroupstofacilitatethetestingofthesystem'sfunctionality. 123

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CIRCEDewarCableMap. 124

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7.2.1 )andthemovingmechanismssystem(Subsec. 7.2.2 ). 7-2 ).ThevacuumgaugeisdirectlyconnectedtoaPfeifferPressureMonitorTPG-261locatedinsidethetemperatureandpressurechassisthatsitsinsidetheLCU 125

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7.3 ).ThepumpdowntimeinCIRCEis5hours,afterwhichthecoolingdownprocesscanstart.UnlikethepumpdownprocessinCIRCE,thecooldownprocessisanon-controlledprocess.Oncenitrogenisintroducedinsidethetankbeamsattachedtotheopticalbench,theentirecooldownprocessonlydependsontheheattransferrateofthedifferentcomponentsoftheinstrument.MostofthecomponentsofCIRCEopticalbench,tankbeams,mirrorsandbrackets,focalplanemechanism,andlterboxarefabricatedwiththesamematerialAl-6061guaranteeingsameheattransferrateandphysicalcontraction.Allthosecomponentsreachuniformcryogenictemperaturesinsidethedewarin24hours.However,componentsmadeofadifferentmaterialthanaluminummotors,opticalelements,Hawaii-2arrayhavelowerheattransferrates,therebyincreasingthecoolingdowntimetoatotalof36hours.Thehousekeepingelectronicscontinuouslymonitorsthetemperatureoftheopticalbenchthrough8on-housemade2N2222diodetemperaturesensors(Fig. 7-3 ).ThesetemperaturesensorsaredistributedaroundtheopticalbenchanddirectlyconnectedtotheLakeshoreTemperatureMonitorLS-218locatedinsidethetemperatureandpressurechassisthatsitsinsidetheLCUrack(Sec. 7.3 ).Thetemperaturesensorsaretheonlysystemthatnotiestheuserwhentheinstrumentisreadyforproperoperation,i.e.,thattheinstrumentisundercryogenicconditions.Thehousekeepingelectronicsisalsoresponsibleforathirdprocess:thewarmupprocess.Thewarmupsystemacceleratesthewarmupprocessbyintroducingheatinthedewar,thusreducingsignicantlythetimenecessaryforopeningtheinstrumentafteranobservation.AlthoughCIRCEisdesignedtochangeobservationmodesduringanobservationwithoutrequiringtheopeningofthedewar,CIRCEisnotexemptfromthatinsomecases,suchasamaintenanceorspecialneedsoftheobserver,theinstrumentneedstobeopenedbetweenobservations.Withoutthewarmupsystem,theonlysourceofheatforincreasingthetemperatureofthedewarafteroperationisthe 126

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7-3 ).Eachheaterconsistsof3in-series155Ohmscartridges,providing104Wattsperheaterforatotalof520Watts.Withtheheatcapacityfortheinstrumentequaling45MJoules,thewarmuptimeisreducedfrom72hoursto24hourswhenintroducingasourceofheatof520Wattsinsideofthedewar.Thewarmupprocessiscontrolledthroughthewarmupbox(Fig. 7-4 ),whichisexternallyattachedtothedewarandprovidesthepowertofeedupthewarmupheaters.AOmegaCN8551-RTD-DC1TemperatureControllerandanOhmitrolSolid-StatePowerControlSwitchallowformanualcontrolofthetotalpowertransferredtothedewarthroughtheCI-9101cable.ThewarmupprocessisprotectedwithaSELCOmodulelocatedinsidethedewar.TheSELCOmoduleautomaticallydisconnectsthewarmupheaterswhenthetemperatureinsidethedewarrisesabove300Kavoidingoverheatingoftheinstrument.Besidesbeingresponsibleformonitoringandcontrollingthepumpdown,cooldown,andwarmupprocessesoftheinstrument,thehousekeepingelectronicsisalsoresponsibleformonitoringandcontrollingthetemperatureofthemostdelicatepartoftheinstrument,theHawaii-2sciencearray.Thesciencearrayhasthelowestheattransferrateofallthecomponentsoftheinstrument,whichmeansthatitisthelastcomponenttoreachtheworkingtemperatureduringthecooldownprocessaswellasthelastcomponenttowarmup.Forthatreason,thehousekeepingelectronicshas 127

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WarmupBoxCableMap.

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7.3 ).ConnectedtotheLakeshoreLS-331,twotemperaturesensorsalongasmallin-housemadeheaterarededicatedtothecontrolofthetemperatureinthesciencearray.Asmentionedabove,thetemperatureandpressureinsidethedewararemonitoredandcontrolledthroughthetemperature&pressurechassis(Fig. 7-5 & 7-7 ).Fourdifferentcomponentssitinsidethischassis:LakeshoreCryogenicTemperatureControllerLS-331,LakeshoreTemperatureMonitorLS-218,PfeifferPressureMonitorTPG-261,andaFibertoSerialCommandInterface.ThetemperaturecontrollerLS-331hastwochannelsfortemperaturesensorinputs,andonechannelforwarmupheaterpoweroutput,andisdedicatedtotemperaturestabilizationofthesciencearray.ThetemperaturemonitorLS-218isan8temperaturesensorinputsusedtomonitorthetemperatureinthedewarinterior.ThepressuremonitorTPG-261communicateswiththepressuregaugeconnectedtothedewartomonitorthepressureinsidethedewar.Thelastcomponentofthetemperatureandpressurechassisisthebertoserialcommandinterface,whichispartoftheoriginalreadoutelectronicsandwillberemovedinthenalcablemaps.Eachoneofthosecomponentshasanindependentcircuitbreakerforprotection,andanon/offstateLEDlights.Thetemperature&pressurechassisisconnectedtothedewarthroughcablesCI-4103,CI-4105,andCI-4113. 7-2 ),themovingmechanismsfocalplanemechanism(Subsec. 5.1.2.2 )andlterboxmechanism(Subsec. 5.1.2.1 )allowswitchingbetweenthedifferentobservingmodes.AllmotorsusedinCIRCEarestepperPortescapP532 129

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LCU:Temperature&PressureChassisCableMap.

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LCU:MotorChassisCableMap.

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7.3 ),andcanbedisconnectedindividuallyorbyblockstofacilitatethetestingofthedifferentsystems.Thefocalplanemechanismisanin-outtranslationmechanismthatallowstheintroductionofthedifferentspectroscopicslitsand/orthepolarimetrichalfwaveplate(HWP)infrontofthelightbeam.Thefocalplanemechanismincorporatesonemotortolinearlytranslatethestageinandoutofthelightpath,andonemotortorotatetheHWP.Twolimitsswitchesindicatewhenthestageistotallyinandtotallyout,andonehomeswitchindicatesareferencepositionfortherotationoftheHWP.Meanwhile,thelterboxisarotarymechanismthatincludes3lterswheels,onegrismwheel,andoneLyotwheel.Eachwheelismovedbyamotor,andreferencedbyahomeswitch.Finally,thethirdcomponentofthemovingmechanismsystemisthewindowcovermechanism.Thewindowcoversystemisamechanismthatmovesaprotectioncoverplateinfrontoftheentrancewindowwhentheinstrumentisnotoperational.Thecoverplateismovedbyasinglemotorwithtwolimitswitchesinandoutandonehomeswitchforreference.Thefocalplaneandlterboxmechanismshavebeenalreadybuiltinourshopandhaspassedrecentlytherstsetofwarmtesting.Thefocalplanemechanismhasalsogoneundercryogenictestingwithexcellentresults,withthelterboxmechanismnextinourqueuetoundergocryogenictesting.Differently,thewindowcoverisstillintheinitialphaseofdesignalthoughprevisionfortheelectronicshasbeendonebasedtheexperienceacquiredfrompreviousinstrumentssuchasFlamingos-2.Asseenabove,allmotorsareconnectedtothemotordrivechassis(Fig. 7-6 & 7-8 )locatedwithintheLCUrack.Themotordrivechassiscontainsalltheelectronic 132

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TopviewoftheTemperature&PressureChassis.PhotocourtesyofLassoCabrera,NestorM. TopviewoftheMotorChassis.PhotocourtesyofLassoCabrera,NestorM. 133

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134

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7-9 showsadiagramoftheconnectorvacuumandcoldplatesaswellastheirlocationinthevacuumandcoldshields.ThehermeticD-subconnectorsmountedontheconnectorscoldplatefacilitatetheconnectionofthecablesbyusingthestandardmateD-subconnectors,howevertheSeries-IIIconnectorsmountedontheconnectorvacuumplatecanonlybeconnectedtothemateconnectorsintheexternalsideoftheplate.TheinternalsideoftheSeries-IIIconnectorspresentslongpinstoconnectthecables,i.e.,non-standardconnectors.Tosolvethelackofstandardconnectorsinthissideoftheplate,afanoutboard(Fig. 7-10 )isattachedtoallthepinsoftheSeries-IIIconnectors.ThefanoutboardredirectsallthesignalsfromthepinstostandardD-subconnectorsmountedonthesamefanoutboard.Thissolutionallowstheuseofstandardconnectorsatthesametimethatincreasethestiffnessoftheentiresystem.Theconnectorvacuumandcoldplateswillbealsousedtointroduceinsidethedewarthesignalsfromthereadoutelectronicsonceanaldecisionabouttheintegrationofthissystemisreached.Thereadoutelectronicswilluseforthatpurposethefreelowerhalfoftheplates. 7-2 7-11 ,& 7-12 )isanelectronicracklocatedbesidethedewarandthatcontainsalltheelectronicssystemsnecessaryforconnecting,monitoring,orcontrollingthedifferentcomponentsoftheinstrumentfromtheobservercomputer.AllthefunctionsoftheLCUarecontrolledbytheinternalSPARCModuleSUNFIREV210computer.Thiscomputercontainsthesoftwarethatrunsthemotors,controlsthetemperatureofthesciencearray,andmonitorsthetemperatureandpressureofthedewarinterior.TheSUNFIREcomputerisremotelycommandedfromtheobservercomputerthroughtheobservatoryprimarynetwork.Forsafetypurposes,anobservatorysecondarynetworkisdirectlyconnectedtoaMOC100BTNetworkSwitchwhichisarequirementoftheGTCandthatwillbeprovidedbytheGTC. 135

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ConnectorVacuumPlate.

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FanoutBoardSchematics. TheSUNFIREcomputerisalsodirectlyconnectedtoanEthernetSwitchthatallowsthecreationofaninternalprivatenetworkonlyaccessibletotheCIRCEteam,andwhichisolatesthedifferentcomponentsoftheLCUfromexternalcommands.ConnectedtotheEthernetSwitchaBayTechRPC3A-16ACPowerControlModuleallowsremotecontroloverthepowerofthecomponentsdirectlyconnectedtoit:motorindexers,Lakeshoretemperaturecontrollerandmonitor,Pfeifferpressuremonitor,SerialCommandInterface,andThermalEnclosureTemperatureControlModule.AlsoconnectedtotheEthernetSwitch,aPERLECS9000SerialPortTerminalServerallowscommandsofthecomponentsdirectlyconnectedtoitthroughserialportconnections:TRIPPLiteUPSModule,motorindexers,Lakeshoretemperaturecontrollerandmonitor,Pfeifferpressuremonitor,andSerialCommandInterface.TheTRIPPLiteUPSModuleofferscompletepowerprotectionoftheLCUcomponentsincaseofgeneralpowerfailure.TheLCUrackispoweredbydirectconnectiontotheobservatorypower 137

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7.2 .TheLCUrackisenclosedinathermalenclosurethatthermallyisolatestheLCUelectronicsrack(Fig. 7-13 ),reducingtoaminimumtheheatradiationfromtheelectroniccomponentstowardthedewar.Asideeffectofthethermalenclosureisthattheinternaltemperatureincreasesbeyondspecications(15C).Inordertomeetspecicationsoftheinternaltemperatureoftherack2Thermatron721SLM2and1Thermatron723SLP2airtowaterheatexchangersareplacedatthebaseoftheLCUrack.Theheatexchangersarecooleddownwith7Cand1GPMcoolingliquidcomingfromthetelescopefacilitiesandregulatedusingaSitzowatervalveexternallyactivatedatthesametimethattheheatexchangers.Thiscombinationofheatexchangersdissipatesatotalof2150Wcompensatingtheheatradiationinsidetherack.Tobeinthesafeside,thetotalheatradiationoftheelectroniccomponentsoftheLCUisconsideredtobethesumofthepowerconsumptionofeachindividualcomponent,whichisequivalentto2015W.Hence,thecombinationofheatexchangerschosenisenoughtocompensatetheheatradiationoftheLCUcomponents,andthereforetocooldowntherackinteriortotheworkingtemperatureof15C.TheLCUthermalenclosurealsoincorporatesa1Amp.circuitbreakerprotection,anon/offstateLEDlight,andamanualpowerswitch.AllthecomponentsoftheLCUracksitprovisionallyinatemporaryelectronicrack(Figs. 7-11 & 7-12 )untilthenalthermalencloseisbuilt.Fig. 7-14 showsthelocationofthedifferentcomponentsinthenalthermalenclosureaswellasdimensionsoftherack.Theblankpanelatthetopoftherackisanemptyspaceleftinprevisionoffutureneedsofthenalreadoutelectronics(Sec 7.4 ). 138

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LCURackFrontView.PhotocourtesyofLassoCabrera,NestorM. 139

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LCURackRearView.PhotocourtesyofLassoCabrera,NestorM. 140

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LCU:ThermalEnclosureTemperatureControlCableMap.

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LCURackDesign.

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Looseetal. 2003a ).ThereductioninthepowerconsumptionoftheH2RGisachievedusingCMOStechnology,whichonlyrequires3.3voltsinputsinsteadofthe5voltsinputsrequiredbytheoldHawaii-2.ThischangeinthetechnologyofthesciencearraypreventstheuseoftheinitialreadoutelectronicsdesignedforCIRCEtheMCE-3(Ch. 6 )tocontrolthereadoutprocessoftheH2RG.InreplacementoftheMCE-3,theCIRCEteamiscurrentlytestinganewreadoutelectronicsdevelopedbytheInter-UniversityCenterforAstronomyandAstrophysics(IUCAA)inPune,India,whichisbasedonamodicationoftheSIDECARTMASICFocalPlaneElectronicsdevelopedbyTeledyne.BoththeH2RGandtheSIDECARASICsystem,aswellastheIUCAAsystemusedinCIRCE,areprotectedundertheInternationalTrafcinArmsRegulations(ITAR),limitingourcapacitytodescribethosesystems.Thus,toavoidanypossibleITARconict,wehavedecidednottoincludeanyspecicdescriptionofthosesystemsinthisdocument,andweencouragethereaderto

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Looseetal. ( 2003a b 2006 2007 ),& Ramaprakashetal. ( 2010 ).CIRCEwillincorporateareadoutelectronicsbasedonthecommercialSIDECARASICsystemprovidedbyTeledyne.TheSIDECARASICisaFocalPlaneArray(FPA)controller,fullycompatiblewiththeH2RGandotherimagearrays( Looseetal. 2003b 2006 2007 ),thatisbecomingthestandardcontrollerinastronomicalinstrumentationbecauseisdesignedtooperateinawiderangeoftemperatures,from30Ktoroomtemperature,withlowpowerconsumptionandhighnoiseimmunity,thusfacilitatingitsintegrationinsidecryogenicdewars.ThecommercialSIDECARASICsystemprovidedbyTeledyneconnectsononesidedirectlywiththeH2RGandontheothersidewithaJADE2cardwhichisreplacedbytheIUCAAsysteminCIRCEthatactsasaUSB-2interfacebetweentheSIDECARASICandtheacquisitioncomputer.TheJADE2cardisdesignedtoworkatroomtemperatureandisconnectedtothecryogenicSIDECARASICthroughasingle15inchexcablealsoprovidedbyTeledyne.ThismeansthattheconnectionbetweentheSIDECARASIC,whichisdirectlyconnectedtothesciencearrayatcryogenictemperature,andtheJADE2card,whichislocatedoutsidethedewaratroomtemperature,hastobedonewithasingle15inchexcablenointermediateconnectorstoguaranteeproperoperation.TheuseofasinglecabletoconnecttheSIDECARASICandJADE2cardhindersitsintegrationoncryogenicsystem,suchasCIRCE,wherealltheelectronicsignalsenteringorleavingthedewarpassthroughthecoldandvacuumshieldbymeansofhermeticconnectors.However,TeledynehasproposedtheCIRCEteamasolutionforthisproblembasedontheirexperienceintegratingtheSIDECARASICsysteminotherastronomicalinstruments,e.g.,theMulti-ObjectSpectrometerforInfra-RedExploration(MOSFIRE)beingbuiltbyUCLAfortheKeckItelescope.Teledyneproposesthecreationofacustomconnectorconsistingofanaluminumplatethatwillbesealedagainstthedewarwithano-ring,andwithagrooveinthecenterforpassingthe15inchexcablethrough.Oncethe 144

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Ramaprakashetal. 2010 ).TheISDECboardiscurrentlyalsobeingintegratedintootherastronomicalinstrument,theRobertStobieSpectrograph(RSS-NIR)beingbuiltattheUniversityofWisconsinfortheSouthernAfricanLargeTelescope(SALT).TheISDECboardconnectstotheSIDECARASIC,allowingtheentiresystemtoworkundertheLinuxoperatingsystem,whichisthestandardoperatingsysteminastronomicalobservatories,andinthenearfuturewillallowthecaptureofhighratesubframes,thusovercomingsomeofthelimitationsfoundwhenusingtheJADE2card.Nevertheless,theISDECboardstillpresentsthelimitationoftheconnectiontotheSIDECARASICthroughasingle15inchexcable.TheCIRCEteamiscurrentlyworkingwithTeledynetoimplementthecustomconnectorsolutionforthisproblem.AspartofthiscollaborationwithIUCAAtoobtaintheISDECboard,IservedastheleadingengineerontheUFside.Tofacilitatethephysicalandscienticintegration 145

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7.5 ,whilecryogenictestingwillstartassoonasthecustomconnectorproposedbyTeledyneisnished.TheSIDECARASIC-ISDECboardsystemhasanominalpixelrateof100Kpix/s,withaframereadouttimeof1.3s,slightlyfasterthantheMCE-3nominalpixelrateof82Kpix/sandframereadouttimeof1.6s(Ch. 6 ).TheIUCAAsystemalsoallowspixelratesupto500Kpix/swiththecorrespondentincreaseonthereadnoise.DuringmystayinIndia,wealsostartedaprojecttoincorporateintheIUCAAsystemafastphotometrymodesimilartotheoneincorporatedbytheMCE-3(Ch. 6 ).IUCAAengineersarecurrentlyworkingonthedevelopmentofthefastphotometrymode,whichisexpectedtobeincorporatedtothesysteminthecomingmonths.ThefastphotometrymodewillacquireimagesatahigherratethanthestandardoperationmodebymeansofreadingsubframesofthesciencearrayinasimilarwaythantheMCE-3fastphotometrymodeandwillalsobenetfromtheISDECboardoptionthatallowshigherpixelrates.Toguaranteealowreadnoise,thefastphotometrymodewillbelimitedtoamaximumpixelrateof200Kpix/s.ThefastphotometrymodeoftheSIDECARASIC-ISDECboardwillallow256x256pixelsubframeratesof12Hz,i.e.,16timesfasterthanthestandardimageacquisitionmode.A12HzframeratewillenableustouseCIRCEtostudytheinfraredemissionofGRS1915+105withatimeresolutionneverachievedbefore,thusallowing 146

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ComparisonoftheMCE-3options3and4framerates(Tab. 6-2 )versustheISDECboardframerateswithpixelratesof100Kpix/sand200Kpix/s. DetectorsizeMCE-3MCE-3MCE-3ISDECISDECOriginalOption3Option4100Kpix/s200Kpix/s 2048x20480.625Hz-0.76Hz1.53Hz512x512-2.13Hz4.3Hz3.05Hz6.10Hz256x256-8.5Hz8.5Hz6.10Hz12.21Hz ustocompletethestudyoftheickeringinfraredjetinitiatedinChapter 4 .Table 7-1 showsacomparisonoftheexpectedsubframeratesfortheMCE-3options3and4seeninChapter 6 versustheexpectedsubframeratesfortheSIDECARASIC-ISDECboardsystem. 147

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Looseetal. 2003a )inthatmode,leavinganupperlimitof5ADUfortheIUCAAsystem.ToquantifytheperformanceoftheISDECboardsystemtwosetsoftestshavebeenrun:readnoisevs.pixelrate,andreadnoisevs.exposuretime.Thereadnoisevs.pixelratetest(Fig. 7-15 )showsthattheISDECboardsystempresentsvaluesofreadnoiseforthenominal100Kpix/spixelrateof<4ADU,i.e.,withinspecications,andwiththeexpectedincreaseofthereadnoisewithpixelrate.Above300Kpix/sthereadnoisepresentsadroponthevaluesindicatingamalfunctionofthesystem,notrelevantforitsincorporationintoCIRCEbecauseCIRCEwillneverusesuchhighpixelrates;thismalfunctionwillbefurtherinvestigatedbytheIUCAAteam.Asexpected,thereadnoisevs.exposuretimetest(Fig. 7-16 )showsnovariationofthereadnoisewithexposuretime.ThesetwotestsconrmthattheIUCAAsystemmeetstheacceptablereadnoiselevelsimposedbytheCIRCEteamwhentheSIDECARASICisatroomtemperature.ThisisapromisingrststepbeforetestingthesystemwiththeSIDECARASICattheworkingtemperatureof77K.Finally,anothersetoftestshasbeenrunontheIUCAAsystem.ThistestquantiestheperformanceofthedevicewhenconnectingtheSIDECARASICtotheISDECboardwithtwoin-series15inchexcablesinsteadofone.AlthoughTeledyneandIUCAAonlyguaranteeproperoperationoftheirdeviceswhenusingasinglecable,instrumentssuchasMOSFIREareusingtwoexcables.TheincorporationofasecondcablewillgivetheIUCAAsystemtheadequatelengthtoplacetheSIDECARASICinsidetheCIRCE'sdewarwiththeISDECboardexternallyattachedtoconnectorvacuumplate,thusnotrequiringanymajormodicationonthedesignofCIRCEaswouldbethecaseifusingasinglecable.Thetwocablesroomtemperaturetest(Fig. 7-17 )showsaminimalincreaseofthereadnoiseof<0.02%atthenominalpixelrateof100Kpix/s,andof<1 148

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4 .TheIUCAAsystemiscurrentlybeingtested,withinitialverypromisingroomtemperaturetestsshowingreadnoiselevelwithinspecications.ThenaldecisionabouttheintegrationofthissystemintoCIRCEwillbetakenbasedontheresultsofthecryogenictestsofthesystemthatwillbeperformedinthecomingmonths. 150

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Readnoisevs.pixelrateforasinglecableand32outputs.Readnoiseincreaseswithpixelratesupto300Kpix/s.Thelowreadnoiselevelsobtainedforpixelratesabove300Kpix/sindicatesomekindofmalfunctionatthoserates. Readnoisevs.exposuretimeforasinglecableand32outputs.Readnoiseisconstantwithexposuretime. Readnoisevs.pixelrateforsingleanddoublecableand32outputs.Thetestislimitedtothenominalpixelratesof100Kpix/sand200Kpix/sforstandardreadmodeandfastphotometrymode,respectively. 151

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Edwardsetal. 2008 ; Charcos-Llorensetal. 2008 ; LassoCabreraetal. 2008 2010 ).TheuniquecombinationofthelargecollectionareaoftheGTCandthehighthroughputopticsofCIRCEwillproducenear-IRastronomicalobservationswithanimagequalityneverseenbeforefromground-basedobservatorieswithoutadaptiveoptics.ThehighthroughputdesignoftheopticalsystemofCIRCEisoneofthemostcriticalcomponentsoftheinstrument.Toensurehighimagequality,andtoconservethehighsignal-to-noise(S/N)levelsprovidedbytheGTC,veryrestrictivespecicationshavebeenplacedonthedesignandalignmentoftheopticalsystemofCIRCE.TheCIRCEopticalsystemhasbeenguredandalignedusinganinnovativesolutiondevelopedjointlybytheCIRCEteamandthemanufacturingcompanyJanosTechnology.Thisnewtechniquetestsandadjuststheopticalsystemasaunitoncealltheelementshavebeenmountedonthebench.Insteadofproducing8individually-testeddiamond-turnedmirrors,thissolutionproducesatestedintegratedsystemfulllingthespecicationsforthewholeopticalsystem,eveniftheindividualmirrorsareslightlyoutoftheirspecications.Thetechniquerequiresallopticalelements,bench,andbracketstobemadeofthesamematerialtoensurehomologouscontractionofthesystem,reducingtoaminimumthedeviationscreatedbycontractionswhenthesystemiscooleddowntocryogenictemperatures.Thistechniqueguaranteesconservationoftheopticalaberrationsofthesystematdifferenttemperatures,allowingtestingoftheimagequalityatroomtemperatureandvisiblewavelengths. 152

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8-1 showsthediffractionpatternsofthe8mirrors.WeestimatedthesurfaceroughnessusingMarechal'sapproximation( Ross 2009 ).TheMarechalapproximationusesvaluesoftheStrehlratiotoobtainthesurfaceroughnessRMSinwaveswith10% 153

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Measuredsurfaceroughnessversusspecicationforeachindividualmirrors. MirrorMeas.RMS(A)Spec.RMS(A)Result Fold112075Outofspec.Fold220075Outofspec.Coll140100AcceptableColl2108100AcceptableImag1125100MarginalImag240100AcceptableImag336100AcceptableImag440100Acceptable Notes.SomeregionsofFold1hadsurfaceroughness>200ARMS. error,Eq. 8 .TheStrehlratioisameasurementoftheopticalqualityofasystem.TheStrehlratioiscalculatedastheratiooftheamountoflightcontainedintheAirydiskofthediffractedimagevs.atheoreticalperfectmaximum.Table 8-1 showsthevaluesofthesurfaceroughnessmeasurementsinAngstroms.Theexpectednominalsurfaceroughnessforeachindividualmirrorisbetween75and100ARMS,withatotalsurfaceroughnessfortheopticalsystemof<265ARMSorlower.OurcalculationsconrmedthatthemirrorsCollimator1and2,andImager2,3,and4meetspecications;Imager1ismarginallyabovespecications;andthetwoFoldmirrorsarewellabovetheexpectedvalues.Thecombinedsurfaceroughnessofallmirrorsis29530ARMS,slightlyabovethenominalspecicationsforthecompletesystem.WeconrmedourresultsofthesurfaceroughnessofthetwofoldmirrorsusingaprolometerlocatedatthelaboratoriesoftheDepartmentofMechanicalandAerospaceEngineeringattheUniversityofFlorida.Theprolometershowedsurfaceroughnessvaluesintherange150to250ARMSforbothfoldmirrors.Althoughthosetwomirrorsdonotmeetspecications,thesurfaceroughnesstestisinconclusivebecausethecombinedsurfaceroughnessofthewholesystem29530ARMSisonlyslightly(10%)abovespecications. 154

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Diffractionpatternsofthereectedimagesofeachindividualmirror.Fromtoptobottom,andlefttoright:Fold1,Fold2,Collimator1,Collimator2,Imager1,Imager2,Imager3,andImager4.Sidelobesareseeninthemirrorswiththehighervaluesofsurfaceroughness. 155

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PinholemaskusedfortestingtheimagequalityofCIRCE. cameraonatwo-dimensionalcomputerizedtranslationstagelateraltranslationandfocustranslationandmanuallymovedthecameraintheverticaldirection.Thetestswerecarriedoutusingapinholemasklocatedatthetelescopefocalplane.Themaskcontains37pinholesspatially-distributedovertheentire3.4x3.4arcminFOV.Eachpinholehasadiameterof170m,simulating0.2arcsec(2pixelsoftheIRarray)stars.Fig. 8-2 showsthepinholemaskusedfortheimagequalitytest. 8-3 showsthethrough-focusimagesofthecentralpinhole.Asexpectedfromthesimulations,astigmatismisthedominantsourceofaberrations.Theelongationofthespotchangesdirectionsastheimagespassthroughthefocalplane,andisminimumandnegligibleatthebest-focuslocation. 156

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Opticalaberrationsofthecentralpinhole.Theimagescoverarangeof200malongtheopticalaxis,centeredonthebest-focusimage,withincrementsof20m.Fromlefttorightandfromtoptobottom,imagesstartwiththefarthestfromlastmirrorpositionandnishwiththeclosestfromlastmirrorposition.Astigmatismisthedominantsourceofaberrationsastheimagesmoveperpendiculartothefocalplane. 157

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Measurementsoftheeldcurvatureatthefocalsurfacelocation.Weobtainedthebest-focuslocationofallpinholesinrows9,10,11,13,and15.Theexpectedeldcurvatureof250misobservedatthecenteroftheeld. cameramountedonthetranslationstagestoobtainthebest-focuspositionofalltheimagesofthepinholesin5differentrowsofpinholes.Fromtoptobottom,wemeasuredrows9,10,11,13,and15,whichcoverapproximatelyhalfofthefocalsurface.Fig. 8-4 showsthemeasurementsofthebest-focuslocationfortheimagesofthepinholes.OurresultsareconsistentwiththeZEMAXsimulations.Theyshowtheexpectedcurvatureofthefocalplane,withamaximuminthecenterof250m.Thus,ourresultsconrmthatCIRCEwillcompensateforthepositivecurvatureintroducedintheimagebytheRitchey-ChretiendesignoftheGTC. 158

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Imagequalityresults.Measurementofthe0.2arcsecpinholeimagesFWHM.Rightcolumnshowstheresulttranslatedto0.3arcsecimages. FieldFWHM(arcsec)FWHM(arcsec)LocationRaw/Instrumental0.3arcsecseeing Center0.220/0.0920.31Center-LeftEdge0.225/0.1040.32Center-RightEdge0.250/0.1500.34TopEdge0.238/0.1390.33Top-LeftCorner0.203/0.0320.30Top-RightCorner0.217/0.0830.31BottomEdge0.232/0.1170.32Bottom-LeftCorner0.334/0.2670.40Bottom-RightCorner0.207/0.0530.31 inthequalityoftheimageslowerthanthebest-seeingattheGTCsite,i.e.,CIRCE'simagequalityisalwaysseeing-limited.ThemostimportanttestperformedontheopticalsystemquantiestheFWHMof0.2arcsecsimulatedstarsinordertoanalyzethequalityoftheimagestakenbyourinstrument.WemeasuredtheFWHMofseveralofthe0.2arcsecpinholesimagesdistributedaroundtheentireFOV.WefoundthattheFWHMvaluesoftheimagesrangefrom0.2to0.25arcsecacrossmostofthedetector,withaslightincrement(0.334arcsec)inthebottom-leftcorner.Thecenterandtopimageshaveexcellentquality.Assumingabestseeingof0.3arcsecFWHM,wewouldexpectdeliveredimagequalityof0.33arcsecover90%ofthearray.Thatisonlya10%degradationoftheimage.Table 8-2 showsthevaluesoftheFWHMofthe0.2arcsecpinholeimagesat9differentpositionsspreadovertheFOV.Italsoshowstheexpectedvaluesforabestseeingof0.3arcsec.Fig. 8-5 showsthe0.2arcsecpinholeimagesusedtomeasuretheimagequality.FromtheFWHMtest,weconcludethattheimagequalityofCIRCEisverygood,ifnotquitetothenominalCIRCEgoals,especiallyintheBottom-LeftCorner.Thebelow-expectedresultsofthisnaltestledustofurtheranalysisofthemirrorswithhighersurfaceroughness.WefoundthattheFoldmirror1presentsasurfaceroughnessof250AmintheBottom-LeftCorner,higherthantheaveragesurface 159

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Representative0.2arcsecpinholeimagesat9differentpositionsacrosstheFOV.Fromtoptobottomandlefttoright:Top-LeftCorner,TopEdge,Top-RightCorner,Center-LeftEdge,Center,Center-RightEdge,Bottom-LeftCorner,BottomEdge,Bottom-RightCorner.Allimageshave<0.25arcsecFWHM,exceptBottom-LeftCorner. roughnessforthatmirrorof120Am.WeconcludethatthisvalueofsurfaceroughnessintheBottom-LeftCorneroftheFoldmirror1explainsthedegradationintheimagequalityofthatportionofthenalimage.Basedonalltheresultsofthetestpresentedhere,theCIRCEteamhasdecidedtoredothediamond-turningofthelowerqualityFoldmirrors.Weexpectthatoncethosetwomirrorsarewithinspecicationsthequalityofthewholesystemwillimprovebeyondthe0.3arcsecFWHMspecications. 160

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NestorLassoCabrerawasbornandgrewupformostofhislifeinLanzarote,CanaryIslands,Spain.HeattendedtheUniversidaddelaLaguna,CanaryIslands,Spain,wherehegraduatedasanElectronicEngineer.DespitelivingundertheexcellentskiesofCanaryIslandsandsharinghislifewithanastronomymajor,hewasalwaysmoreinterestedintakingapartelectronicdevicesthanhewasinlookingtotheskies.Thischangedin2006whenhiswifebegangraduateschoolattheUniversityofFlorida.There,heknewabouttheastronomicalinstrumentationprogramandtheinstrumentstheywerebuildingforsomeofthelargesttelescopesintheworld.Ayearlater,NestoralsobegangraduateschoolattheUniversityofFlorida.HestartedworkingwithDr.StephenEikenberryonthedevelopmentoftheCanariasInfraRedCameraExperiment(CIRCE),anearinfraredinstrumentforwhatiscurrentlytheworld'slargesttelescope,theGranTelescopioCanarias(GTC).HealsostartedhisresearchonthestudyoftheX-rayandIRvariabilityofstellarmassblackholes.AfterreceivinghisPh.D.fromtheUniversityofFloridainthesummerof2012,hewillmoveontoUniversidaddeConcepcion,Chile,tocollaboratewithDr.NeilNagarinthedevelopmentofabeamformerfortheAtacamaLargeMillimeter/submillimeterArray(ALMA). 177