http://www.iucaa.ernet.in/~astrosat/
ASTROSAT Science and synergy with NuSTAR
Dipankar Bhattacharya IUCAA http://www.iucaa.ernet.in/~astrosat/ LAXPC UVIT
SXT
CZT
Star Sensors
Phased Array Antenna SSM UVIT capabilities
FUV: 130 - 180 nm (~7-10 eV) NUV: 200 - 300 nm (~4.1-6.2 eV) VIS: 320 - 550 nm (~2.2-3.9 eV)
Effective Area: ~15 cm2 (FUV) ~50 cm2 (NUV / VIS)
Typical sensitivity: mAB ~ 20 Typical resolution: ~ 1.8 arcsec HEXTE, ISGRI LAXPC LAXPC
SXT LAXPC
CZTI
SXT http://www.iucaa.ernet.in/~astrosat/ ASTROSAT Key Niche • UV imaging • X-ray timing: Only mission with high resolution timing capability immediately after RXTE • Simultaneous multiwavelength variability: UV-X ray correlation • Sensitive hard X-ray spectroscopy: e.g. Cyclotron lines • Wideband spectrum: UV, 0.3-150 keV ASTROSAT will be an observatory class mission, driven by proposals received from the user community http://www.iucaa.ernet.in/~astrosat/ ASTROSAT Key Niche • UV imaging - study of star forming regions, extinction, mid-redshift Ly-break galaxies, SFR history Galaxy images from the GALEX satellite
ASTROSAT will be able to obtain images with 3-4 times better resolution http://www.iucaa.ernet.in/~astrosat/ ASTROSAT Key Niche
• X-ray timing: Only mission with high resolution timing capability immediately after RXTE • Simultaneous multiwavelength variability: UV-X ray correlation Detailed analysis of intensity variations as a function of time, energy and other properties of the system
=> Mass and spin of black holes and neutron stars. State of matter at high density. GR effects. http://www.iucaa.ernet.in/~astrosat/ Timing with ASTROSAT
• Periodic phenomena: pulsars, orbital variations • Quasi-periodic/aperiodic variations • Correlation of power spectra with energy spectra and luminosity states • Large range of time scales: sub-ms to months • Large range of energy scales: 10-3 to 102 keV http://www.iucaa.ernet.in/~astrosat/
Energy dependence of High Frequency Quasi-Periodic Oscillation amplitude 4U 1608-52 Berger et al 1996; Gilfanov et al 2003 !"#$%&'$()**+%)',$&-"#),.&
/012&Burst3&45 Oscillations#+0&6"#$%$
Time (s) /7&8%#'9:+02#&;<<=
3:1'#%+,%>>?&@2&.2%&%92&81),&A#2B"2,(0>>> Upper QPO frequency from innermost allowed orbit: ISCO / NS radius
=> Constraints on NS EOS
Time (s) Strohmayer et al 1996
Thampan, Bhattacharya, Datta 1998 Major emission components in accreting Black Hole sources XTE J 1550-564 Spectral / Luminosity states of accreting BH
Zdziarski & Gierlinski 2004 XTE J 1550-564 Spectral / Luminosity states of accreting BH
Power spectrum of intensity variation is seen to depend on the spectral state
Zdziarski & Gierlinski 2004 XTE J 1550-564 Spectral / Luminosity states of accreting BH
Power spectrum of intensity variation is seen to depend on the spectral state
Transition from hard to soft state appears to be correlated with the launching of jets
Zdziarski & Gierlinski 2004 XTE J 1550-564 Spectral / Luminosity states of accreting BH
Power spectrum of intensity variation is seen to depend on the spectral state
Transition from hard to soft state appears to be correlated with the launching of jets
ASTROSAT will have excellent capability to study this phenomenology Zdziarski & Gierlinski 2004 http://www.iucaa.ernet.in/~astrosat/ ASTROSAT Key Niche
• Sensitive hard X-ray spectroscopy: e.g. Cyclotron lines Astrosat will be a very sensitive instrument for cyclotron lines. Phase resolved spectroscopy to map magnetic structures in accreting pulsars can be carried out
Vigelius & Melatos 2008 Paul 2004 http://www.iucaa.ernet.in/~astrosat/ ASTROSAT Key Niche
• Broadband spectroscopy: e.g. Magnetar spectra
Magnetar spectra are -10 multi-component,
time-variable and /s) 2 -12 poorly understood.
Simultaneous broadband (erg/cm -14 coverage essential for E F(E) detailed study -16 log
-18 den Hartog et al 2006 -8 -6 -4 -2 0 2 4 log E (keV) Multiwavelength science: AGN :: Disk photons+Compton
Spectral pivoting and Comptonization cycle UV - correlated variability
log Flux expected - No detailed study so far
X
log photon energy Multiwavelength science: AGN :: Blazars
3C 279
Compton: upscattered photons Synchrotron: seed photons Multiwavelength science: CVs :: Accretion on Magnetic WDs
cold supersonic optical/IR flow Multi-temperature plasma cyclotron radiation - Multiple emission components shock - Simultaneous multiwavelength
spectra can reveal the ongoing hard X-rays physical processes hot postshock soft X-rays/ flow extreme UV
white dwarf http://www.iucaa.ernet.in/~astrosat/ ASTROSAT Key Niche • Wideband spectrum: UV, 0.3-150 keV Simulated Broadband spectrum of Coma Cluster Synergy with NuSTAR LAXPC
CZTI
SXT LAXPC
NuSTAR
CZTI
SXT Synergy with NuSTAR
• Extension of spectral coverage • Timing-spectroscopy complementarity • TOO services • Cross calibration Synergy with NuSTAR
• Extension of spectral coverage NuSTAR will have excellent spectral sensitivity in hard X-ray bands over long exposures ASTROSAT can provide valuable extension to soft X-rays
For a typical E-2 photon spectrum NuSTAR and ASTROSAT SXT will have similar count rates AGN / Magnetars / Galaxy clusters / UV-X studies of starbursts...... Synergy with NuSTAR
• Timing-spectroscopy complementarity ASTROSAT NuSTAR Large Area Low background High countrate High spectral resoln High background Smaller countrate Good for Timing Good for Spectroscopy These two missions may participate in joint spectral-timing and monitoring campaigns, e.g. of BH sources / AGNs / Magnetars / YSOs Cyclotron lines important for both missions: phase resolved / phase averaged Synergy with NuSTAR
• TOO services Many opportunities will arise for TOO observations by both missions. Multispectral coverage important. Higher resolution of NuSTAR can help resolve source confusion in ASTROSAT. Synergy with NuSTAR
• Cross Calibration Simultaneous availability of the two missions will provide an excellent opportunity for cross-calibration in overlapping energy bands. Will be helpful in calibrating the complex response of LAXPC Concluding Remarks
• Both ASTROSAT and NuSTAR will open up several unique science opportunities • These two missions share several common goals. Simultaneous availabiliy will enhance the science of both missions • Should explore means of initiating a collaborative science programme Thank you