AstroSat - India's Multi-Wavelength Astronomy Satellite K.P. Singh Tata Institute of Fundamental Research (TIFR), Mumbai + several colleagues at TIFR and Indian Institute of Astrophysics (IIA), Bangalore Inter-University Centre for Astronomy & Astrophysics (IUCAA), Pune Canadian Space Agency University of Leicester, UK ISRO Satellite Centre (ISAC), Bangalore Raman Research Institute, Bangalore Vikram Sarabhai Space Centre, Trivandrum Space Applications Centre, Ahmedabad Physical Research Laboratory, Ahmedabad KPS@MSSL2015 10/30/15 1 KPS@MSSL2015 10/30/15 2 KPS@MSSL2015 10/30/15 3 ! LaunchedbyPSLV-XLfromSHARonSep28,2015 Altitude:650km;Inclination:6deg. Massof1513kg.(750kg.Payloads)+6moresmallsatellites Power=2200wattsbysolarpanels+2x36AHLi-ionbatteries Heatersandsensorsforthermalcontrolofallthepayloadsand subsystemsasspecified. ! Three-axisstabilization. ! ! ! ! ! Orientationby4reactionwheelsand3magnetictorquers(capacity:60Am2) ! ! ! ! +inputsfrom3dualgimbalgyros,2starsensorsand2magnetometers. Targetacquisitioncapabilityof0.05° Pointingaccuracyof~1arcsecwithstarsensors. Driftrateisexpectedtobe0.2arcsec/s. Maximumslewratewillbe0.6o/s. 10/30/15 KPS@MSSL2015 4 ! Solid-staterecorderwith200Gbstorage(4orbits). ! Asatellitepositioningsystemfortimereferenceof200ns. ! AnASICbasedsystemBusManagementUnitwith1553interfaceswill ! ! ! ! ! ! interfacewithAttitudeandOrbitcontrolsystem,CommandProcessing, HousekeepingTelemetry,SensorProcessing,RCSinterface,Thermal Managementetc. DatatransmissionbytwoX-bandcarriersviatwophasedarrayantennas, onceinallthevisibleorbits,atarateof210(2x105Mb/s)Mb/s.House keepingdatatransmissioninS-bandviaquadrifilarhelixantennas. Thespacecraftcontrol,payloaddataacquisition,dataprocessingfrom groundstationsinBengaluruviz.,ISTRACTTCNetwork,TTC-Bangalore station. IndianSpaceScienceDataCentre(ISSDC)forpayloaddata. Operationallifeof>5years Orbitalperiod:~98minutes; Eclipseperiod:35minutes;Sunlitperiod:62minutes 10/30/15 KPS@MSSL2015 5 AstroSat:Co-alignedmulti-waveinstruments SXT UVIT (IIA+ISAC+CSA+IUCAA+TIFR) (TIFR+UoL+ ISAC+VSSC) LAXPC (TIFR) CZTI (TIFR + IUCAA +VSSC) SSM (ISAC+VSSC) Cold Side with Radiator plates For CCD and CZTI Star Sensors (ISAC) KPS@MSSL2015 10/30/15 6 phase, in the 2.5 -10 keV energy range. Table 1. Performance parameters of ASTROSAT ! ASTROSAT Expected Performance Parameters of the scientific Instruments UVIT Detector! Intensified CMOS, used in photon ! counting mode or ! !!!!!!!!!!!!!!!!!!!!!!!integration mode Imaging Imaging!/!non/ imaging! Twin RitcheyOptics!! Chretian 2 mirror system. 1300-5500 Bandwidth! Angstroms ! ~1100 Geometric!Area! (cm2)! Effective!Area!! 8 - 50 (depends on filter) (cm2)! 28’ dia Field!of!View! (FWHM)! <1000 A Energy! (depends on filter) Resolution! Angular! Resolution! ! Time!resolution! 1.8 arcsec (FUV,NUV) 2.2 arcsec (Vis) 1.7 ms Typical! observation! time!per!target! Sensitivity! (Obs.!Time)! 30 min Mag. 20 (5σ) 200 s (130-180 nm) SXT LAXPC CZTI SSM X-ray (MOS) CCD at the focal plane. (XMM & Swift heritage) Proportional counter CdZnTe detector array Positionsensitive proportional counter Imaging Non-imaging Imaging Imaging Conical foils (~Wolter-I) mirrors. 2-m focal length 0.3 - 8 keV Collimator 2- D coded mask 1- D coded mask 3 - 80 keV 10 - 100 keV 2.5 - 10 keV ~250 10800 1024 ~180 ~128@1.5 keV ~22@6 keV ∼ 40’ dia 8000@5-20 keV 0 1 x 10 1000 (E>10 keV) 60 x 60 ~11 @ 2 keV ~53 @ 5 keV 100 x 900 ∼5-6%@1.5 keV ∼2.5%@6keV ∼2 arcmin (HPD) 12%@22 keV 5% at 100 keV 25% @ 6 keV ~(1-5) arcmin (in scan mode only) 8 arcmin ~12 arcmin 2.4 s, 278 ms 10 µs 1 ms 1 ms 0.5 - 1 day 1 - 2 days 2 days 10 min ~10-13 ergs cm-2 0.1 milliCrab 0.5 milliCrab -1 s (3σ) (3σ) (5 σ)KPS@MSSL2015 (20000 s) 10/30/15 (1000 s) (1000s) ~28 milliCrab (3σ) (600s)7 ASTROSAT UVIT: Configuration Doors Main-baffles Secondary Mirror Sec. Baffle Primary Baffle ~3100 mm TiCone (interface With S/C) Primary mirror (375 mm) Thermal cover (this encloses Detectors and filter-wheels) KPS@MSSL2015 10/30/15 8 UVIT:J.HutchngsPASP(2011),123,833EffectiveApertures (estimates) KPS@MSSL2015 10/30/15 9 UVIT:J.HutchngsPASP(2011),123,833EffectiveApertures (estimates) KPS@MSSL2015 10/30/15 10 ASTROSATSCIENCE:UVITSimulations 630 SRIVASTAVA, PRABHUDESAI, & TANDON M51 galaxy GALEX (spatial scale reduced to put it at 3 times its distance) vs Astrosat FUV Image From stacking of several short exposure images to correct for drift PASP (2009), 121, 621 KPS@MSSL2015 10/30/15 11 LAXPC: Large Area Proportional Counters X-ray timing (10 µsec) low spectral resolution studies A broad energy band (3 - 80 keV) with high detection efficiency • Three co-aligned identical Counters • Each with a multi-wire-multi-layer configuration filled with 90%Xe +10% Methane gas at 1520 torr. Energy resolution (13%@22 keV) • A 50 micron thick aluminized Mylar window for X-ray entrance • Mylar film support -- by a honeycomb shaped window support collimator with 5 x 5 degs field of view • A narrow field of view of 1x1 degs provided by mechanical collimators made of a sandwich of 50µ Sn + 25µ Cu + 100µ Al co-aligned with the window support collimator and sitting above it. • Blocking shield on sides and bottom : 1mm Sn + 0.2 mm Cu KPS@MSSL2015 10/30/15 12 made"up"of"46"anode"cells"each"with"cross6section"of"1.5"cm"X"1.5"cm"surrounds"the"main"X6ray"detection" volume" on" 3" sides" to" reject" events" due" to" charged" particles" and" interaction" of" high" energy" photons" in" the" detector."The"alternate"anode"cells"of"Layer"1"and"2"are"linked"together"and"thus"4"outputs"are"obtained"from" Layer"1"and"Layer"2.."The"anode"cells"in"each"of"the"Layer"3,"4"and"5"are"linked"together"to"provide"one"output" from"each"layer."Thus"there"are"7"anode"outputs"that""are"operated"in"mutual"anticoincidence"to"reduce"the" non6cosmic"X6ray"background"The"Veto"layer"is"divided"in"3"parts"providing"3"Veto"Layer"outputs."The"left"side" 60 anode cells 3 cm x 3 cm x 100 cm in 5 layers each 15 cm deep (12 anodes/layer). and"right"side"veto"anodes"are"linked"together"to"provide"one"output"from"each"one"and"the"third"veto"output" Mutual & layer by layer anticoincidence + Veto layers of 46 anodes cells (1.5x1.5 cm) is"from"the"bottom"layer"veto"anodes"linked"together."" 1600 wires – tension 80 gm per wire " ASTROSAT LAXPC " " 13 KPS@MSSL2015 10/30/15 A"50"micron"thick"aluminized"Mylar"film"serves"as"the"gas"barrier"as"well"as"the"X6ray"entrance"window"for"the" detector."The"detector"is"filled"with"a"mixture"of"90%"Xenon"+"10"%"Methane"at"a"pressure"of"1520"torr."The" ASTROSATLAXPCunit(~125Kg) KPS@MSSL2015 10/30/15 14 SXT:FPCA+Optics(~65Kg) KPS@MSSL2015 10/30/15 15 SXT:Optics–ReplicatedThinfoilmirrorsmadein TIFR(followingSuzaku) 2 m focal length; ~2 arcmin HPD; 40 shells (130 – 260 mm dia); Only 12 Kg ! Mirror roughness 7 – 10 Angstroms : Exp. Ast. (2011), 28,11 KPS@MSSL2015 10/30/15 16 Modified from Swift; Using spare MOS CCD22 from XMM: 600 x 600 pix, 40 microns • Four Fe-55 calibration (corner) sources • One Fe 55 calibration door source • Thin Optical Blocking Filter • CCD Assy. including TEC • PCB with front-end electronics KPS@MSSL2015 10/30/15 17 ReadoutModesoftheCCD (1) Photon Counting Mode (PC), [The Default Mode - includes the calibration sources] (2) Photon Counting Window Mode (PCW), (3) Fast/Timing Mode (FM), (4) Bias Map Mode (BM), and (5) Calibration Mode (CM). ! X-ray spectral information available in all the modes. ! Time resolution in the PC, PCW, CM modes is 2.4 s, and 0.278 s in the FM mode. ! FM reads only the central 150x 150 pixels of the CCD. ! For observing very strong cosmic sources, the PCW mode should be used to avoid pile-up followed by the Calibration mode where four small windows (each of size=80 x 80 pixels) covering only the corners are used for the corner radioactive sources in the CM. ( A central 100x100 window is also used in the CM). KPS@MSSL2015 10/30/15 18 SXT Flight FPCA CCD Door and Corner X-ray Calibration Sources Optical LED Image Very good – only 2 hot pixels KPS@MSSL2015 10/30/15 19 SXTFM:Electronics:NIM:A(2009),604,747;Energy Calibrationspectrummeasuredusinginternalsources:SinglePix events,alltypesofevents.CCD@-80C 4.5 keV (Ti-F) 4.15, 4.75 keV Mn-K Esc 1.48 keV (Al-F) 1.74 keV (Si-K) 2.6 keV (CL-F) KPS@MSSL2015 10/30/15 20 FMCALIBRATIONat-80C:Measuredwith InternalFe-55sourcesandresponsemodeled Target Energy Res. %ge (FWHM, eV) Al –Flo 1487 eV 90 +- 8 6.0+-0.5 Si –K 1740 eV 92 +- 6 5.1+-0.3 Cl –Flo 2621 eV 104+-5 4.0+-0.2 Mn-Kα esc 4155eV 120+-5 2.0+-0.15 Ti -Flo 4511 eV 2.8+-0.15 126+-6 Mn-Kβ esc 4750 eV 128+-7 2.7+-0.15 Mn-Kα 5895 eV 135+-9 2.3+-0.15 Mn- Kβ 6490 eV 140+-10 2.1+-0.15 KPS@MSSL2015 10/30/15 21 ASTROSAT CZT-Imager Size: 482 x 458 x 603 mm Heat pipes CFRP support Weight - 50 kg Power – 60 Watts Collimator fov: 6o x 6o 976 cm 2 (64 CZT modules x 15.25 cm2 in 4 quadrants); No. of pixels: 16384; 2.4 mm X 2.4 mm (5 mm thick) ; ASIC based (128 chips of 128 channels) Radiator Optical cube Alpha tag source CZT bottom hsg. Handling brackets CAM (Tantalum)255 pseudo-random Hadamard Collimator Side joining plates CZT top hsg. CZTI: Calibration & Veto ! An X-ray source (Am241) mounted in a gap of 8 cm between the base of the collimator slats and detector plane in each quadrant for calibration. ! VETO Detector: CsI (Tl) 20 mm thick x 165 mm x 165 mm detector viewed by two photomultipliers in a flat geometry. Just under the CZT modules. " LLD: 50 keV. Variable by command: 256 steps of ~ 10 keV. " Uniformity: ~ 10%, " Response time: 5 µs " Typical dead-time: 20 µs; A few hundred µs for saturated peaks NIM:A (2010), 616, 55 KPS@MSSL2015 10/30/15 23 CZTI: Modes Normal mode SAA mode Shadow mode Reduced data mode " Fixed no. of events " Block veto spectrum " 2 word event report ! Secondary spectral ! ! ! ! 1s 0-9 packets/quadrant 100s 1 packet/quadrant 100s 1 packet/quadrant 1s 1s 1s 100s 0-9 packets/quadrant 0-9 packets/quadrant 0-9 packets/quadrant 2 packets/quadrant Charged Particle Monitor – to monitor the SAA entry and exit to lower voltages of the LAXPC CsI + Si-pin photodiode; LLD of 1 MeV & can be reset KPS@MSSL2015 10/30/15 24 CPMdetectsSAA(Oct.1,2015) KPS@MSSL2015 10/30/15 25 of" the" incident" photon." " The" position" (P)" of" the" incident" photon" on" the" detector" plane" is" given" by" P=(VL6 VR)/(VL+VR)"*C1+C2,"where"VL"and"VR"are"the"amplitudes"of"the"left"and"right"output"pulses"and"C1"and"C2"are" Scanning Sky Monitor the"calibration"constants"of"that"particular"anode"on"which"the"photon"is"incident."" " (SSM) The"SSM"detector"plane"consists"of"two"layers"of"wire6cells,"central"eight"of"the"top"layer"being"active"anode" cells."The"two"edge"cells"of"the"top"layer"and"the"ten"cells"in"the"bottom"layer"are"all"connected"together"to" form"the"background"or"veto"layer."The"information"that"we"get"about"every"photon"that"is"incident"on"the" detector"are"1."Time"of"arrival,"2."Energy"and"3."Position"of"incidence.""All"the"three"parameters"are"measured" using"the"electronics"system"of"SSM." " Design of Mask Six"different"coded"mask"patterns"could"be"generated"for"the"constraints"set"in"the"specifications"of"SSM,"with" 50%"transparency.""They"are"joined"sideways"and"the"resulting"complete"mask"plate"is"shown"in"figure"4.""The" design" of" the" coded" mask" and" the" deconvolution" software" is" developed" in" collaboration" with" Prof." D." Bhattacharya"of"IUCAA." Three rotating Units: PSPC + coded mask The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again. Figure!6.5!:!The!coded!mask!plate!with!six!different!mask!pattern!used!in!each!of!the!three!SSM!cameras.! KPS@MSSL2015 10/30/15 26 AstroSatStatus&SwitchONSequence ! ChargeParticleMonitor(CPM)forSAAmonitoringisONand ! ! ! ! ! ! ! working LowVoltageSystemsforPEswitchedonforSXT,CZTI& LAXPC:StatusOK SXTcameraventinggoingondailyfor10mins CZTIHighVoltage-5thOct,andfirstlight–Oct6th(Crab simultaneouswithSwift) SSMOn:12thOct. SXT:TECONforCCD(Oct9)andTelescopeDooropening(15 Oct)andCameraDoorOpeningandfirstlight(Oct27) LAXPCHVONandfirstlight(Oct17) UVITON(Nov26th) KPS@MSSL2015 10/30/15 27 Astrosat–PostlaunchMissionPlan ! 1styear " First6months–PVPhase(4X-ray;2UV) " Next6months–GTPhase(4X-ray;2UV) ! 2ndyear " 5%Canada,3%UK,5%TOO,2%Cal,35%OpenforGO(India), 50%Instruments’GT ! 3rdyear " 5%Canada,3%UK,5%TOO,2%Cal,45%OpenforGO(India), 30%Instruments’GT,10%OpenforInternationalGO ! 4thyear " 5%Canada,3%UK,5%TOO,2%Cal,65%India(GO),20% InternationalGO KPS@MSSL2015 10/30/15 28 ASTROSAT – several multi-wave instruments co-aligned for # SimultaneousOpt-NUV–FUV-softX-ray-hardX-ray measurements # LargeX-raybandwidth,betterhardX-raysensitivity thanRXTE # LowbackgroundX-raydetectors:nearEquatorial Launch # BrightsourcecapabilityinsoftX-rays # UVimagingcapabilitybetterthanGALEX KPS@MSSL2015 10/30/15 29 ASTROSAT:AcomparisonwithotherX-ray Satellites Energy (keV) KPS@MSSL2015 10/30/15 30 SciencewithX-rayInstruments ! Accretion–WhiteDwarfs(CVs),NeutronStar BinariesandBlackHoles(galactic,extragalactic– AGN). ! Physicsofastronomicaljets(Blazars),magnetic fields(Cyclotronlines)etc. ! Physicsofhotcoronalplasmas:HardX-ray componentsandflares ! Synchrotron,InverseComptonemissionprocesses KPS@MSSL2015 10/30/15 31 ASTROSATSCIENCE:X-raySimulations Hercules X−1 (Astrosat) 4U 1636−536 Exposure==12.5 50 ks Exposure ks (F) ASTROSAT−Simulation 3C454.3 SED of AGN: Blazars, Seyferts 100 1000 100 10 Model: phabs*powerlaw (nH = 6.5E+20 cm−2, Indx = 1.6, Norm = 2.6E−02) Black: SXT(0.3−8.0keV): 27.5 cps wabs*NPEX*cyclabs Red: LAXPC(3−80keV): 753.4 cps [Enoto et al., PASJ, 60, 57, 2008] Green: CZTI(10−100keV): 1.8 cps SXT wabs*(bbodyrad+bbodyrad+comptt) 3 LAXPC [Fiocchi et al., ApJ, 651, 416, 2006] 10 10 1 Count Green: Rates CZTI(10−100keV): 74.3 cps SXT: 3.07 ct/s wabs*NPEX Histogram: model: 3 CZTI: 4.4 ct/s Data points: Simulated data LAXPC: 121.7 ct/s 0.1 1 0.01 0.1 −1 keV −1 Counts Counts ss−1 keV−1 Black: SXT(0.3−8.0keV): 1.3 cps Red: LAXPC(3−80keV): Exposure: 10 ks 1697.0 cps CZTI 3 Flux −4 10 0.01 10−3 0.1 0.01 Simulation MCV 10−4 10−3 Simulation XRB, Cyclotron lines from neutron stars in X-ray binaries. normalized counts s−1 keV−1 1 2 SXT(0.5−10 keV): 1.78E−10 ergs−11cm−21s−1 2 Dotted lines : model components CZTI(10−100 keV): 3.95E−10 ergs−1 cm−2 s−1 1 : 1st blackbody LAXPC(3−80 keV): 4.39E−10 ergs−1 cm−2 s−1 2 : 2nd blackbody 3 : Comptonization Ref: Wehrle et al., ApJ, 758, 72 (2012) 11 1 2 10 10 10 Energy (keV) Energy (keV) Energy (keV) KPS@MSSL2015 100 100 100 10/30/15 32 Acc. Disks in AGN – UV/X-ray continuum Laha, GCD, AKK, SC 2013 IRAS 13349+2438 Done et al. 2013 Disk Disk PG 1244+026 OM Mrk 509 FUSE HST/COS EPIC-pn Mehdipour et al. 2011 Disk dominated AGN! High/Soft State of AGN!!! KPS@MSSL2015 10/30/15 33 Non-ThermalEmissioninClustersof Galaxies:Motivation The X-ray emitting thermal plasma in a virialized cluster loses most information on how the formation proceeded due to the dissipative processes driving the plasma towards a MaxwellBoltzmann momentum distribution characterized by its temperature only. Non- equilibrium distributions of cosmic rays preserve the information about their injection and transport processes much better, and thus provide a unique window of current and past structure formation processes. Information about these nonequilibrium processes is encoded in the spectral and spatial distribution of cosmic ray electrons and protons. Radiative loss processes of these non-thermal particle distributions produce characteristic radio synchrotron, hard X-ray inverse Compton, and hadronically induced γ-ray emission. KPS@SAAO 2015 10/30/15 34 Motivation(contd.) Non-thermal Radio emission is seen as: Radio Relics: Have a high degree of polarisation, are irregularly shaped and occur at peripheries of the clusters -- can be attributed to merging or accretion shock waves. Radio Haloes: Resemble the regular morphology of the Xray emitting intra-cluster plasma and are poorly understood. Where is the non-thermal X-ray and γ-ray emission ? KPS@SAAO 2015 10/30/15 35 Non-thermalprocessesin Cosmic rays in clusters of galaxies – II. Ra clusters KPS@SAAO 2015 10/30/15 lines. Occ On macros diffusion p scopically can be reg tangled ma E < 2×1 the order o Berezinsky to diffuse filling dist tion is an a the ICM. The C CR energy 36individual ticle as we HardX-ray(20-80keV)Tails: Balloon+Satellitebasedmeasurements Beppo-SAX: Nevalainen et al. 2003 Relaxed Fig. 3.— The non-thermal signal and 1σ uncertainties in PDS 20 – 80 keV band after subtraction of the contributions from the background, thermal gas and AGN in the field, and after propagating uncertainties due to these subtractions. The dotted vertical line separates the relaxed clusters (left) from the rest (right). KPS@SAAO 2015 10/30/15 37 Swift/BAT:JointlywithXMMNewton Ajello et al. 2009, 2010 20 Clusters studied: Perseus, A3266, A754, Coma, A3571, A2029, A2142, Triangulum, Ophuchius, A2319; A85, A401, Bullet, PKS 0745-19, A1795, A1914, A2256, A3627 (Norma), A3667, A2390. All best described by multi-temp thermal model except Perseus and Bullet (4.4σ) which show hard X-ray excess consistent with Chandra Observations for Bullet, and AGN: NGC 1275 in Perseus. KPS@SAAO 2015 10/30/15 38 t the results. The spectral fitting results are ble 2. Newton and Suzaku Spectral Fits Without Considering Systematic Errors usly fit the Suzaku HXD-PIN and XMMspectra for the PIN FOV. First, we consider perature fit, in order to establish whether the hermal component actually improves the fit d a best fit temperature ± 0.06 keV, Wik et of al.8.45 2009; l agreement with similar fits to the PIN data nd XMM dataAlso (8.37 see: ± 0.12 keV) individue dip at 15 keV is a known problem with Suzaku model (Mizuno et al., Suzaku Memo 2008observations of by the spectrum is individually described X-ray excess perature, the existence of excess emission emission in the s unlikely. While all of these temperatures cluster average A 3112temperature r than the cluster-wide al. in this and es et al. 1993),T.theLehto energyetrange ly extends to energies 2010 below 2 keV and thus w temperature gas. $ Basically: a power-law Cannot non-thermal component prorule out better description of the spectra, according the presence of oving the overall fit (Table 2), but only for a NT emissionand !! power law 0. Allowing the temperature PIN. Shown as solid lines are the best fit models for a single temperature thermal component. The thermal model (“APEC", green) is nearly coincident with the data, though falling below it at higher energies. Also included for all joint fits are the the total spectrum for the “XMM Point Sources" (red) and the Cosmic X-ray Background (“CXB", purple), the latter of which only applies to the PIN spectrum since the CXB is subtracted from the XMM data along with the NXB. Suzaku+XMM:ComaCluster (A1656) ry along with each component’s normaliza8.42 ± 0.06 keV and Γ = −1.6, though Γ is d. If we fix Γ to this best-fit value, the IC ificant at the 2.2σ level without considering matic uncertainties. However, this photon F IG . 5.— Suzaku HXD-PIN spectrum (E > 12 keV) and the combined XMM spectrum (E < 12 keV) corresponding to the spatial sensitivity of the PIN. Shown as solid lines are the best fit models for a single temperature thermal component plus a non-thermal component. The thermal model (“APEC", green) is nearly coincident with the data, though falling below it at higher energies. The non-thermal model (“Power Law", light blue) is the faintest model component for both spectra, and the photon index is fixed at Γ = 2.0. The other two components are described in Figure 4. KPS@SAAO 2015 10/30/15 for E > 40 keV results in a best-fit power law component very 39 only very standard ent backing from χ2red PF−test a kT [keV] FluxHXR b CLHXR σc Method 1 0.93 2 · 10−4 8.56+0.37 −0.35 10.1 ± 2.5 4.0 Method 2 1.05 7 · 10−5 8.50+0.48 −0.45 8.2 ± 1.3 6.4 Ophiuchus:2ndbrightestX-ray cluster(kT~9-10keV) Integral Detection at 4 to 6.4σ level: Eckert et al. 2007 10−4 10−3 0.01 0.1 Consistent with Suzaku (Fujitsa et al. 2008), Beppo-SAX, Swift/ BAT upper limits ! −2 0 2 4 normalized counts/sec/keV χ er of the V (white) V image. he cluster osition of Chandra The errors are quoted at the 1σ level. c Confidence level for the detection of the non-thermal component. 5 10 20 channel energy (keV) 50 Fig. 7. JEM-X/ISGRI combined spectrum in the 3-80 keV band. The solid line is a fit to the 3-20 keV part of the spectrum with a single-temperature MEKAL model. The bottom panel shows the residuals from the model. The hard X-ray excess is clear. spectrum and the residuals from the thermal 40NXB by ±5% (cros KPS@SAAO 2015 10/30/15 Fig. 7. HXD PIN spectra, including the effect of varying the normalization of the The NXB has been subtracted. The fit (solid line) is for the normal NXB. The lower panel plots model with temresiduals divided by the 1σ errors. ComaClusterwithAstroSat KPS@MSSL2015 10/30/15 41 BulletCluster:NuStar(266ks): Wiketal.2014 NuSTAR Observations of Very hot kT ~ 15.3 keV, and no evidence for a NT component above 20 keV Fig. KPS@SAAO 5.— The ratio spectrum (crosses, using the 42 nominal 2015of the 10/30/15 background model; all spectra from Figure 3 have been combined for clarity) to each model. The red/dark and green/light shaded regions are the same as in Figure 4. Although difficult to tell, the 2T h o n b n k fl t w h o U t e a a m t b o t i c Chandra:TheBulletCluster 8 E. T. Million and S. W. Allen non-thermalsurfacebrightnessandPLindex Figure 2. (a) left panel: Spatial map of the surface brightness (in erg cm 2 s 1 arcsec2 ) of non-thermal-like X-ray emission in the Bullet Cluster, 1E 0657-56 (z = 0.297). A power-law component is only included in regions where it is statistically required at greater than 90 per cent significance (Section 3.2). The 1.34 GHz radio surface brightness contours from Liang et al. (2000) are overlaid in black. (Radio point sources have been removed). (b) right panel: Map of the photon index of the power-law components, with the radio surface brightness contours overlaid. Only regions with ‘non-thermal’ surface brightness greater than 10 16 ergs s 1 cm 2 arcsec 2 are shown in this map. Each spatial region has ⇠ 104 net counts in the 0.6 7.0 keV Chandra band. KPS@SAAO 2015 eter). The nominal temperatures of the additional emission components are typically high, with kT2 > ⇠ 15 keV. 3.2 10/30/15 Detailed spatial mapping of the ‘non-thermal’ components 43 Chandra:TheBulletCluster RESULT: Spatial correlation between the regions of the brightest non-thermal radio halo emission, brightest thermal X-ray emission, and strongest non-thermal-like X-ray signatures in the central regions of 1E 0657-56 KPS@SAAO 2015 10/30/15 44 Summary&Challengesahead The presence of non-thermal hard X-ray emission in clusters of galaxies remains controversial. Existing limits on this component suggest a small magnetic field of the order of 0.1µG, which is in stark contrast to the Faraday rotation measurements which demand much stronger intracluster magnetic field of order of a few µG (Clarke,Kronberg,Bo ̈hringer,2001;Carilli and Taylor,2002). Several possible explanations: Two most likely options in this regard could be the simplest ones: either the reports of detections of nonthermal X-rays are not correct, or they are correct but the nonthermal X-rays are not of IC origin. To establish the presence or absence of this component, we will need: Hard X-ray telescopes with: High Spatial resolution, Wide field, Low-to-medium energy/spectral resolution & Large area KPS@SAAO 2015 10/30/15 45 Thanks! Website : astrosat.iucaa.in KPS@MSSL2015 10/30/15 46