ASTROSAT Dipankar Bhattacharya IUCAA, Pune Astronomy Meeting IUCAA, Pune, 21 Sep 2017
AstroSat An Indian Astronomical Observatory based in Space Launched on 28 Sep 2015 atmospheric opacity 0% 50% 100% ASTROSAT wavelength wikipedia 0.1 nm 100 nm 100 μm 10 cm 10 m 1 km
LAXPC 3-100 kev X-ray Timing, broadband spectroscopy SXT 0.2-8 kev imaging & line spectroscopy ASTROSAT UVIT 1.4 UV imaging CZTI 20-250 kev hard X-ray imaging, timing, spectroscopy PI: S. Seetha (ISRO) PMs: S.N. Tandon (UVIT), J.S. Yadav (LAXPC), S. Bhattacharyya (SXT) A.R. Rao (CZTI) M.C. Ramadevi (SSM) Star Sensors LAXPC: TIFR, RRI SXT: TIFR, ISRO, UoL CZTI: TIFR, ISRO, IUCAA, RRI, PRL SSM: ISRO, IUCAA, RRI UVIT: IIA, ISRO, IUCAA, CSA SSM rotating 2-10 kev monitor Phased Array Antenna 1450 kg Spacecraft: ISRO Operations: ISRO Ground software: ISAC, SAC, TIFR, RRI, IIA, IUCAA, NCRA, PRL ISRO
10000 AstroSat co-aligned payloads: effective areas Effective Area (sq.cm) 1000 100 SXT RXTE PCA LAXPC CZTI Effective Area (sq. cm) 50 40 30 20 10 FUV UVIT Filters NUV 0 100 200 300 400 500 600 wavelength (nm) VIS 10 0.1 1 10 100 1000 Photon Energy (kev) Individual photon recording in all bands High time resolution: 10μs (LAXPC), 20μs (CZTI), 1.6ms (UV), 287ms (SXT) Simultaneous operation ~2ev to 150keV All sky transient monitoring at > 100 kev Hard X-ray polarisation capability (100-380keV)
Integrated AstroSat before launch weight: 1.5 ton PIC: ISRO PSLV XL Rocket weight: 320 ton
ASTROSAT orbit 650 km altitude, circular, 6 deg inclination, Period 98 min SAA Wikipedia worldsmapsonline.com
Operations commands data raw data LAXPC: TIFR, RRI UVIT: IIA ISTRAC, PEENYA ISSDC, BYLALU science products POCS SXT: TIFR CZTI: IUCAA SSM: ISAC, IUCAA DATA ARCHIVE USER PROPOSALS ASTROSAT SCIENCE SUPPORT CELL REVIEW, TIME ALLOCATION, SCHEDULING Proposal streams: GT, AO : annual cycles TOO, Cal: always open
Operations Oct 2015 - March 2016 : Performance Verification and calibration April 2016 - Sept 2016 : First Science run (Guaranteed Time for Instrument Teams) Oct 2016 onwards : Indian Open Time Oct 2017 onwards : International Open Time Observing proposals are invited for annual cycles, peer reviewed and time is allocated on the basis of the review outcome. Target of Opportunity observations may be proposed at any time
Glimpses of Results
A.R. Rao et al
Test of AstroSat Timing capability Crab Pulsar AstroSat LAXPC + CZTI Crab Nebula Pulsar: X-ray bands 80-250 kev Pulse Period: 33.72 ms Phase bin: 100 μs Data resolution: 10-20 μs normalised intensity 30-80 kev 10-30 kev CXO 2-10 kev 0 0.2 0.4 0.6 0.8 1 phase D. Bhattacharya
Crab Nebula Pulsar: UV band 20 15 UVIT NUV Crab Pulsar Background counts 10 5 0 0.2 0.4 0.6 0.8 1 Phase Exposure: 221 s Resolution: 1.6 ms
Crab Nebula Broadband Spectroscopy: Crab Nebula normalized counts s 1 kev 1 100 10 1 0.1 0.01 10 3 10 4 SXT LAXPC Common spectral model power law, photon index 2.11 CZTI (data model)/error 4 2 0 2 4 1 10 100 Energy (kev) Anjali Rao K.P. Singh
Imaging and spectroscopy with Soft X-ray Telescope Diffuse Remnant of Tycho Brahe s Supernova (SN 1572) Astrosat SXT, 6 Nov 2015 K.P. Singh et al Si S
NGC 2336 GALEX
NGC 2336 Astrosat UVIT NUV Dec 2015 S.N. Tandon, J. Postma et al
Spectral signature of a binary star in NGC 188 5e-14 SED for star S1 2e-14 1e-14 UVIT UIT GALEX UBVRI JHK Log (Flux) 5e-15 2e-15 1e-15 5e-16 S.Annapurni et al 2000 5000 1e4 2e4 Log (wavelength)
Globular cluster NGC 1851: UVIT FUV time lapse image S.Annapurni et al Detection of RR Lyrae Variable stars: 10 min exposure each, separated by ~14 h
Cygnus Loop Optical image Hα Steve Cannistra
Cygnus Loop Optical image Hα UVIT FUV Steve Cannistra SXT spectrum Sutaria, Rahna, Murthy, Singh, Rao, Tandon Flux (ct/s/kev) Mg Si 0.5 Energy (kev) 1.0 2.0 UVIT NUV Singh et al
Accreting Supermassive Black Hole in Active Galaxy NGC 4151 Fe line X-ray reflection from accretion disk G.C. Dewangan et al
Normalised Count/s/keV Data/(Model w/o Absorption) 100 10 1 0.1 1 0.8 Cyclotron Resonance GX 301-2 AstroSat LAXPC 40 ks 5 10 20 40 Energy (kev) Data Model Suman Bala
khz QPO detection by LAXPC Orbit and frequency 2.6 Shifted power in 3-20 kev band 840 820 800 Hz 2.5 2.4 2.3 500 1500 2500 sec 15 km 4U 1728-34 8 March 2016 Power 2.2 2.1 28-Sep-16 Jai Verdhan et al 2016 J S Yadav, TIFR 2 1.9 1.8 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Frequency (Hz) Chauhan et al 2017
Photons cm 2 s 1 kev 1 10 4 10 3 0.01 0.1 1 Accreting Black Hole Cygnus X-1: Spectral Variations Dec 2015 Oct 2015 SXT The Astrophysical Journal, 835:195 (6pp), 2017 February 1 1 10 100 Energy (kev) CZTI LAXPC Figure 8. Photon index vs. flux for flux resolved spectra at a timescale of 1 s. index clearly shows a correlation with flux changing by nearly 0.1 for a factor of two variation in the flux, at a remarkably fast timescale of 1 s. The variation of the otherdec spectral 2015para- meters, such as those of the disk component, are within errors. Clearly, tighter constraints can be obtained once the background and the response of the detectors is better modeled. The analysis shows that LAXPC data can be analyzed using more sophisticated techniques like frequency Oct 2015resolved spectroscopy where spectra corresponding to different frequency variation are generated (Revnivtsev et al. 1999, 2000; Reig et al. 2006) and also by the alternate technique known as timescale resolved spectroscopy, where the analysis is undertaken in the time domain (Wu et al. 2009). Such an analysis can reveal spectral variations, such as that the spectral index correlates with flux for Cygnus X-1, on timescales as short as 64 msecs (Wu et al. 2010). However, these analyses have been limited to few of the Misra et al 2017 S.V. Vadawale et al clearly shows index factor variabi This in driven Compt truncat would variatio the low compo photon flux) a variatio time de observ For rapidly there is with e frequen high a the cas indicat variatio inner model. The that LA X-rays observ combin
Cygnus X-1: Power Spectrum 3-10 kev Misra et al. AstroSat LAXPC 20-40 kev Misra et al 2017
Gamma Ray Bursts with ASTROSAT CZTI Chattopadhyay et al GRB 151006A First cosmic source detected by AstroSat was a GRB They signal birth of Black Holes AstroSat can detect polarisation of high-energy (> 100 kev) emission of Bright GRBs (~5/yr) > 100 GRB detections reported so far from AstroSat Positive detection of polarisation in 7 cases in the first year Estimated polarisation fraction between 48% to 96% Upper limits placed in 4 cases, lowest 35% A.R. Rao et al
AstroSat CZTI search for EM counterpart of GW events At energies above 60 kev CZTI FOV gradually opens up to the whole sky. Localization Can detect till 250 kev Veto detector sensitive up to 1 MeV Flux Limits
Summary AstroSat is addressing a wide range of science issues Highly capable X-ray timing mission Excellent UV imaging, resolution second only to Hubble Space Telescope Simultaneous wideband spectroscopy Transient detector and monitor Hard X-ray polarisation In operation for past 2 yrs, expected to last > 5 yrs Observing opportunity is open to all, proposals sought
For information http://astrosat.iucaa.in/ http://astrosat.iucaa.in/czti/?q=grb http://astrosat-ssc.iucaa.in/ https://www.issdc.gov.in/astro.html