High Energy Universe Viewed Through Astrosat

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High Energy Universe Viewed Through Astrosat
P.C.Agrawal Tata Institute of Fundamental
Research, Mumbai
Talk at the Chandrayan Symposium at IMSc ,
Chennai , January 4 , 2011
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ASTROSAT A Broad Spectral Band Indian Astronomy
Satellite
An Indian National Space Observatory A
Collaborative Project of Tata Institute of
Fundamental Research (TIFR), Mumbai ISRO
Satellite Centre (ISAC), Bangalore Indian
Institute of Astrophysics (IIA),
Bangalore Inter-University Centre for Astronomy
Astrophysics, Pune. Raman Research Institute,
Bangalore Canadian Space Agency, Canada Leicester
University, U.K. With participation of Many
Indian Universities and research centres
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• Salient Features of Astrosat
• Multi-wavelength observations with four
  co-aligned instruments covering Visible,
  Near-UV, Far-UV, Soft X-ray and Hard X-ray bands.
• Broad Spectral coverage in X-rays from 0.5
  keV to 100 keV for timing and spectral studies
  with 3 X-ray instruments.
• Large collecting area in 2-20 keV ( 6000
  cm sq. ) for timing studies in X-rays.
• Largest area detector for hard X-ray
  studies ( 5000 cm sq. at 50 keV ), important
  for studying high frequency QPOs and non-thermal
  component in Black Hole sources.

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• High angular resolution telescopes ( 2 arc
  sec ) in the UV region. Two telescopes each of
  38 cm aperture, one in Visible and Near-UV and
  other in Far- UV with photon counting detectors
  for high sensitivity observations.
• Soft X-ray Imaging Telescope and CZT Imager
  for medium energy resolution spectral studies and
  localization of Transients in soft and hard
  X-ray bands.
• A Scanning Sky X-ray Monitor to detect and
  monitor Transients and known objects.
• High time resolution (10 µs ) and high count
  rate capability ( 40 k Counts with PHA and 60 k
  Counts without PHA ) with LAXPC instrument.
  

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Astrosat Instruments  Four X-ray Astronomy
Instruments and one Ultraviolet Instrument
With two Telescopes   1. LAXPC Large
Area X-ray Proportional Counters with Aeff
6000 cm2 at 20 keV, FOV 10 X 10,
sensitive in 3-80 keV band with low
spectral resolution (E/?E 5 to 12) .
2. CZT Imager X-ray detector CdZnTe
(Cadmium-Zinc-Telluride) array with a
coded mask aperture having Aeff 500 cm2 and
medium spectral resolution (E/?E 10 to
15 ).
3. SXT Soft X-ray
Imaging Telescope using conical-foil mirrors
with medium angular (3' ) and spectral (E/?E
20 to 50) resolution in 0.3-8 keV
with A eff 200 cm2 at 1 keV.

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4. SSM Scanning Sky Monitor (SSM) using 3
PSPCs with coded mask aperture ,
each with Aeff 30 cm2 and energy
band of 2-20 keV.
  5.
UVIT Ultraviolet Imaging Telescope (UVIT) has
two similar telescopes each
with 38 cm aperture primary mirror
and photon counting imaging detectors covering
simultaneously near-uv , far-uv and
visible bands.


A Charged Particle Monitor (CPM) as an auxiliary
instrument for the control and
operation of the Astrosat
Instruments.  
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Instruments are technically complex and
challenging, they are not commercially available.
In India the design and development of
instruments have to be done in house as expertise
and experience available only with few persons.
Fabrication of flight hardware also mostly done
in house only.
X-ray CCD mounted on Thermoelectric Cooler to be
used for the SXT
LAXPC X-ray detector Anode Assembly with veto
layer on 3 sides mounted on the back plate. 60
Anode cells are arranged in 5 layers to make the
X-ray detection volume. 37 Micron dia. Au-plated
SS wires under tension used for anodes.
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One LAXPC unit undergoing tests in Thermovac
Chamber to simulate space-like environment.
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Sectional View of the Two Telescope configuration
of the Ultra Violet Imaging Telescope (UVIT) for
the Astrosat mission
Soft X-ray Imaging Telescope employs X-ray
Reflecting Optics and an X-ray CCD to record
X-ray Image and measure X-ray energy.
CZT Imager on Astrosat For Hard X-ray
Spectroscopy and Imaging
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UVIT Characteristics

Two similar coaligned telescopes Primary Mirror
aperture 38 cms Secondary 14 cms Focal
length 503 cms f/ratio 13 Configuration
RC with focal plane corrector 90
energy 1 Corrected field 0.5 Passband
Channel I 120-180
nm Channel II 180 300
nm Optical 350-650
nm Detector
Photon counting system
CPM with appropriate read
out for
getting X Y
40 mm x 40 m Pixel resolution
25 µ Material of Mirror
Zerodur
with Al MgF2
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Components in each Detector
Intensifier
(DM)
Fiber Optic Taper
High Voltage supplies
(HVU)
Imaging area 40 mm f QE gt 5 in band
centre Pos. res. lt 100 mm Exposure 10-1000
mSec Frame rate gt 20 Hz Gain 2000 20,000
e-/g Safety electronic gating
CCD/CMOS
(Need High Voltage Power Supplies
up to 8000 V)
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ASTROSAT Top Deck Layout
SXT
UVIT
LAXPC
CZT
SSM
Artists View of the Astrosat Multiwavelength
Observatory
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Study of High Energy Universe by X-ray and UV
Observations

• All types of Galactic and Extragalactic
  objects are UV and X-ray sources
• Galactic Sources
  
• Compact Stars in Accreting X-ray Binaries
• Neutron Stars Both have high
  luminosity in X-rays
• Black Holes and are also visible in
  UV
• White dwarfs ( Bright UV objects as T
  is high)
• Supernova Remnants
• About 200 SNRs in our galaxy .
• Shock heated gas (T 10 5 - 10 7 )
  emits UV and
• X- rays

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Extragalactic Sources AGNs ( Quasars, BL
Lacs , Seyfert Galaxies ) Powered
by massive ( 10 7- 10 9 M O ) accreting Black
Holes in their nuclei
Accretion Disks Around BHs emit UV and X-rays .
There is excess UV from AGNs
(called UV Bump )
Star Burst Galaxies and Star Forming Regions
Nurseries of young stars and pre-main
sequence stars that are copious UV
and X-ray sources
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• Astrosat Science
  Objectives
• Multiwavelength
  Observations
• ASTROSAT will be a powerful mission for
  Multiwavelength
• studies of various types of sources using 5
  co-aligned telescopes
• covering broad X-ray , near- UV , far- UV
  and Optical bands.
• AGNs will be prime targets for this as only
  a small number of bright
• AGNs studied in campaign mode so far.
• Correlated UV , Optical and X-ray variations
  , measure time lags
• and do reverberation mapping.
• Construct energy distribution curves of
  AGNs over 5 decades in
• energy

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Images of the Active Galaxy Nucleus of NGC 4303
(M61) in Optical,UV and X-ray bands. The bright
central object is likely to be a Massive Black
Hole of 100 million Solar mass producing energy
by accretion of matter.
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Light Curves of quasar 3C 273 over 20 year period
in different spectral bands
Fig. 2. Examples of light curves from the 3C
273 database for the last 23 years of
observations, at 5 GHz, 37 GHz, 0.8 mm, in the K
band, in the V band, at 5 keV and in the 2070
keV range (this latter rebinned to 1-month
bins). The data during strong synchrotron flares
(Flag 1) are indicated in grey (red in the
electronic version) for the optical and IR data
sets.
( From S. Soldi et al. AA, 486, 411-425,2008 )
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Multiwavelength light curves from intensive
monitoring of the BL Lac object PKS 2155-304 in
1991 November (Edelson et al. 1995). X-ray data
are from the Rosat PSPC UV data are from the IUE
SWP (short wavelength) and LWP (long-wavelength)
spectrographs optical data are from the FES
monitor on IUE. The emission is closely
correlated at all wavelengths, and the X-rays
lead the UV by 2-3 hours.
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Comparison of the NUV UVW1 and X-ray (0.610 keV)
light curves over the 160 days of Swift
observations of Black Hole source XTE J1817-330.
The NUV flux most closely tracks the X-ray
power-law emission and does not track the total
X-ray flux or the X-ray disk flux
(ApJ,666,1129,2007
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• Astrosat Sience Goals
• High resolution timing studies
• Periodic and chaotic variability, Evolution
  of pulse and orbital periods in X-ray binaries,
  Accreting Millisec Pulsars and AXPs.
• Detection and measurements of of low and
  high frequency QPOs in soft and hard X-ray bands
  in Black Hole and other X-ray Binaries .
• High Freq. QPOs studies put constraints on
  mass and spin of Black Holes.

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Periodicities in Accreting X-ray Binaries
(Neutron Star and Black Hole Systems) P(spin)
msec to 1000 sec , P (orbital) 14 min to 100
days P (QPOs) 0.1 Hz to 1000 Hz , P
(Flicker) 100 ms to 10 mins P(Precession or
disc warping) 10 days to 300 days ( found in
some XRBs e.g. Her X-1 35 days, Cyg X-1 300
days)
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Sub-second Intensity Variations in the
Micro-quasar GRS 1915105 with the Indian X-ray
Astronomy Experiment (IXAE) on IRS-P3 .
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Period vs. Period derivative Diagram for all
known Pulsars
Red Stars are Magnetars
Big Red Star is the new Magnetar SGR 04185729 (
N. Rea et al.,Science,330, 944, 2010 )
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Giant flares from SGRs
LF 1045-1047 erg
SGR 190014 Aug. 1998 Hurley et al. 1999
SGR 1806-20 Dec. 2004 Palmer et al. 2005
Recent result
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• Detection of QPOs above 10 keV in Black
  Hole and Neutron star binaries is an unexplored
  area. QPOs above 10 keV detected so far only in
  3 BH Binaries. kHz QPOs above 10 keV reported
  so far only in GRO J1655-40.
• Do AGNs show Bimodal states similar to
  that of Stellar- mass Black Holes ? Repeated
  observations of AGNs required to answer this.
• Search QPOs in AGNs. Reports of a few
  detections so far.

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QPOs detected in two ULXs (Strohmayer Mushotzky
03 Strohmayer et al. 07) M82 X-1 ??QPO
54-166 mHz NGC5408 X-1 ??QPO 20 mHz Properties
(rms, coherence, noise, variability)similar to
Type C QPOs in BHBs (0.1-15 Hz). Extrapolating
correlations known to exist for BH binaries and
assuming that QPO scales inversely to MBH
(Mucciarelli et al. 06 Strohmayer et al. 07)
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QPOs detected in XMM-Newton light curve of
Narrow-line Seyfert 1 RE J10.34396. QPO Period
3733 s
High-frequency QPOs seen in several BHBs occur in
pairs with the frequency ratio of 328. These
frequencies appear to be stable and are regarded
as a signature of strong gravity in the vicinity
of a rotating black hole18. A tentative
frequency-mass relation, f 0 931 (M/M)-1 Hz,
can be derived from three objects. Here f 0 is
the fundamental frequency of the pair, i.e. the
observed frequencies are 2f0 and 3f0 (the
fundamental is not seen). This relation yields
the black hole mass in RE J1034396 of 6.910e6
or 1.010e7 M, depending on whether the observed
periodicity corresponds to 2f0 or 3f0,
M Gierlinski et al. Nature 455, 369-371 (2008)
doi10.1038/nature07277
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Astrosat Science Goals

• Broad band Spectral measurements
• Spectra of the
  continuum emission from all classes of UV and
  X-ray sources
• Emission and absorption features with medium
  energy resolution capability in 0.3 100 keV
  spectral band with 3 co-aligned X-ray
  instruments.
• Understand the Complex Multi-component energy
  Spectra of galactic and extragalactic Black Hole
  sources to understand the origin of radiation
  from various processes.
• Measuring non-thermal spectral component in
  Accreting NS and BH Binaries,SNRs and AGNs

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Energy Spectra of Black Hole Binary Cyg X-1 and
Neutron Star Binary 4U 1705-44 ( Astro-ph
0909.2572 by Gilfanov)
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Energy Spectrum of SNR Cas A in o.5-100
keV X-ray measurements above 20 keV crucial for
detecting Non-thermal spectral component in X-ray
binaries, SNRs, AGNs and Cluster of Galaxies.
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Average Spectrum of Intermediate Polars . Best
fit kT 20 keV
Energy Spectrum of Seyfert 1 Galaxy IGR 07597
3842 from Integral and Chandra/ XMM-Newton data.
Molina et.al. MNRAS (2009)
Microquasar GRS 1915105 A A,494,229,2009
Power Law index 1.6, Cut off Energy 70 keV
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Energy Spectra of Magnetars measured with
instruments onboard Suzaku in 0.8-70 keV. A
Blackbody thermal component with kT 0.5-1 keV
and a power law component with photon index
0.4-1.7 fit the spectra well ( Enoto T. et al.
Astro-ph 1009.2810 ).
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Astrosat Science Goals

• Measure Magnetic Field of Neutron Stars in
  X-ray Binaries
• From detection and energy of Cyclotron
  lines in the X-ray spectra of
• Pulsars. Cyclotron absorption lines in 12
  60 keV detected in the X-ray
• spectra of 20 X-ray Pulsars
• B ( 2-8 ) 10 12 Gauss
• High resolution ( 2 arc sec ) UV imaging
  studies of Star Burst Galaxies,
• Nornmal Galaxies ,AGNs, Hot stars, SNRs etc.
• Deep UV survey of selected regions of sky
• X-ray scans of Galactic Plane and Center for
  detection of new transients
• and other variable sources
• X-ray Monitoring of Sky for detection of
  Transients, Bursts and Flaring
• activity and studies of persistent sources

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Luminosity (350 keV) dependence of the fundamental cyclotron resonance energies in binary X-ray pulsars, using Gaussian absorption modeling. The other data points for A0535262 refer to Wilson Finger (2005 LX 1.1 1037 ergs s-1), Kretschmar et al. (2005 0.4 1037), Grove et al. (1995 3.6 1037, assuming 110 keV as the second harmonic), and Kendziorra et al. (1994 3.8 1037). The results on 4U 011563 and X033153, both assuming a distance of 7 kpc, are from Nakajima et al. (2006) and Nakajima (2006), respectively.
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Simulation of Cyclotron Lines from Pulsar
4U011563
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Ultraviolet image of Galaxy M 33 with Galex.
Credit NASA/JPL-Caltech/GALEX
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• Astrosat Mission Characteristics
• Pointing accuracy of about 1 arc sec.
• Three axes stabilized well proven satellite
  bus using 3 gyros and 2 star trackers for
  attitude control by reaction wheel system with a
  Magnetic torquer
• Mission life of at least 5 years. Circular
  orbit of 600 km altitude and inclination of
  8.
• Launch by well proven Indian Polar Satellite
  Launch Vehicle (PSLV) from Satish Dhawan Launch
  Center at Shriharikota (India).

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Conclusions

• Astrosat will enable timing observations with 10
  µs accuracy in a broad spectral band of 3-80 keV
  with LAXPCs of A 6000 cm -2 in. 3-20 and 5000
  cm-2 in 20-60 keV bands. Largest area ever used
  for hard X-ray studies.
• Medium energy resolution capability of CZT for
  accurate spectra and detection of cyclotron
  features.
• SXT for imaging and spectral studies for 0.3-8
  keV band.
• Simultaneous observations with co-aligned 3 X-ray
  Instruments covering 0.3-100 keV region to
  construct spectra of sources.

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Obtain multifrequency spectra covering Visible,
UV , Soft X-ray and Hard X-ray regions for a
variety of sources. UV studies and deep UV
survey of selected regions and sources with UVIT
to a limit of m 21st magnitude. Detection
and monitoring of transient and persistent X-ray
sources with SSM.