Transcript ASTROSAT: The Large Area X-ray Proportional Counters

ASTROSAT
Prospects for a Hard X-ray Survey
ASTROSAT Overview
LAXPC Details
Science Prospects
Hard X-ray Survey Prospects
Beyond ASTROSAT
Biswajit Paul
Raman Research Institute, Bangalore
ASTROSAT
IXAE
Large Area X-ray Astronomical Observatories
–EXOSAT-ME : 1983-1986
–1.5-15 keV, 1800 sq cm
–With LE Imaging Telescopes (CMA)
–GINGA-LAC: 1987-1991
–2-37 keV, 4000 sq cm
–With All Sky Monitor
USA Exp,2000 sq cm
IXAE, 1200 sq cm
–RXTE-PCA: 1996-201?
–2-30 keV, 6000 sq cm
–With All Sky Monitor and Hard X-ray Instrument
–ASTROSAT-LAXPC:
–2-80 keV, 6000 sq cm
–With All Sky Monitor, Soft/Hard X-ray Instruments, UVIT
LAXPC Characteristics
Area : 6,000 - 7,500 cm2
Mass: 390 kg
Time Resolution: 10 µs, dead time 10-35 µs
Absolute Timing Accuracy: 10 µs
Front-end and Processing Electronics: separate electronics for each detector
Data Storage: Onboard Memory 570 MB per Orbit
Detection Efficiency: 90-100 % upto 20 keV, ~40% upto 80 keV
Energy Resolution: 12-13% at 20-60 keV
Life Time: 3-10 Years, no Consumable
LAXPC: Effective Area
LAXPC: Complex Energy Response
• Energy response generation:
Monte Carlo simulation / Ground calibration
LAXPC: Energy resolution
Spectral Leakage in PCA and LAXPC
PCA
LAXPC
Spectral Leakage in PCA
LAXPC Schematic
LAXPC: Complex Energy Response
PCA: Energy resolution of single events and escape events
ASTROSAT Ground Trace
LAXPC Advantages
Large effective area in hard X-ray band
Stable background
Low Spectral leakage
Wide energy band
2-80 keV with LAXPC
0.3-8 keV with SXT
10-150 keV with CZT
Simultaneous, sensitive, multi-band UV/Optical observations
Only timing instrument it this time frame
CRSF with ASTROSAT LAXPCs
Hard X-ray QPOs
Long term intensity variations in Cen X-3
Long term intensity variations
and the orbital modulation
Raichur & Paul 2008
Cen X-3: Precessing Warped Accretion Disk ??
Raichur & Paul 2008
Cen X-3: Precessing Warped Accretion Disk ??
Raichur & Paul 2008
Cen X-3: Intensity dependence of the pulsed fraction
Raichur & Paul 2008
Long term intensity variations in Cen X-3
and the quasi-periodic oscillations
Harhsa et al. 2008
Long term intensity variations in Cen X-3
and the quasi-periodic oscillations
Raichur & Paul 2008
Hard X-ray Survey
Explore the 10-60 keV band
Period ic Scan
Galactic plane + SMC region
Extragalactic Survey
100 x 100 degree
Survey with Slew Data
Example: RXTE-PCA
Survey with Slew Data
Survey with Slew Data
X-ray Polarimeter
POLIX: Sensitivity
MDP(n) =(n/S) (2(S+B)/T) 1/2
GEMS