Biswajit Paul

Report
Neutron star observations in
hard X-rays
Hard X-rays are
emitted by
• Accretion powered
pulsars
•Magnetars
•Young rotation
powered pulsars
Missions
•Ginga
•RXTE
•Integral/Swift
•BATSE/GBM
•Beppo-SAX
•Suzaku
2-37 keV
2-25, 20-100, keV
15-150 keV
15/7-50 keV
0.1-100 keV
0.5-150 keV
•Nu-Star
5-80 keV
•Astro-H
•Astrosat
0.5-200 keV
0.5-150 keV
•POLIX
•LOFT
5-30 keV
2-50 keV
Magnetars
•Magnetars 1013-15 Gauss (SGR, AXP)
•Short lived evolutionary track of the magnetars after
birth  good fraction of all neutron stars are probably
born as magnetars
•Highly variable in their X-ray emission properties.
•Huge outbursts once every few decades
•Active phase: bursts with random time difference and
random intensity occur
•X-ray pulses and the pulse profile shows long term
variations, sometimes with associated spectral
changes.
•A a very challenging class  motivated many
theoretical work.
Magnetars
•Strong hard X-ray emission with multiple spectral
components, pulsating differently between them and
differently with the soft component.
•Association with the highest magnetic field radio
pulsars,
•Quasi-periodic oscillations
clue to the internal and crustal structures of the
neutron stars.
•The spin phase dependence of the short bursts of
magnetars.
Magnetar hard X-ray emission
Magnetar hard X-ray emission
Magnetars
•Hard X-ray pulse profiles, pulse profiles of different
spectral components and long term variabilities of all of
these.
•Measurement of hard X-ray spectrum of several
magnetars
•Study of the long term variations of the pulse profiles
and the spectra,
• Test the magnetar models
Young Neutron Stars
•Only a small fraction of the spin-down energy is emitted in the
radio band. Much larger fraction of the spin-down energy in high
energy band, X-rays and Gamma-rays.
•Soft X-ray and amma-ray emission seen in many objects.
•Recently, pulse hard X-ray emissions have been detected in
several pulsars.
•Pulsar modes to be tested over the widest energy band possible.
Rotation Powered Pulsars
Hard X-ray emission
Energy dependent pulse profiles
Accretion Powered Pulsars
Spin-evolution, Quasi-period Oscillations
Orbital evolution, orbital glitches
Broad band spectrum
Energy dependence of pulse profiles
Luminosity dependence of pulse profiles
Cyclotron lines
Cyclotron lines: pulse phase dependence
Cyclotron lines: luminosity dependence
Cyclotron lines: luminosity dependence of the pulse phase dependence
Cyclotron lines: pulse profile dependence of the pulse phase dependence
Energy dependent pulse profiles
Luminosity dependent pulse profiles
Orbital evolution of X-ray binaries
LMC X-4
CenX-3
SMC X-1
4U 1538-52
Double Compact Binaries
Gravitational Wave Emitters
Short Gamma-ray Bursts
XTE J1808-5635
Cyg X-3
XTE J 1810-271
EXO 0748-676
XTE J1710-281
4U 1822-37
Her
X-1
Her
X-1
Cycltron lines
Luminosity dependence
Pulse phase dependence
Dips in Pulse Profiles : Partial Covering Absorption
16
Dips in Pulse Profiles : Partial Covering Absorption
17
NuSTAR
NuStar
Broad band spectrum with good energy resolution
of moderate/faint objects
Long exposure required: limited number of sources
Limited scope for pulse phase resolved studies
ASTRO-H
ASTRO-H
c
Astro-H
Broad band spectrum with good energy resolution
of moderate/faint objects
Micro-calorimeter
Very broad band
Long exposure required: limited number of sources
Limited scope for pulse phase resolved studies
ASTROSAT
IXAE
Indian X-ray Astronomy Instrument
Onboard IRS-P3, 1996
Large Area X-ray Proportional Counter
ASTROSAT Ground Trace
Pulsar Cyclotron lines
Cyclotron lines studies with LAXPC
Chandreyee Maitra 2012
Thermonuclear X-ray Burst Reprocessing
31
Reprocessing in EXO 0748-676: XMM-Newton Observations
Hard X-ray Quasi Periodic Oscillations
Astrosat
Good for moderate/bright sources
time/phase resolved studies
Multi-wavelength observations
Stable background
X-ray Polarimetry
Polarised X-rays
36
Accreting X-ray Pulsars
Image: NASA
Meszaros et al. 1988
37
POLIX
38
X-ray Polarimeter
Polarisation is unexplored in High Energy Astrophysics
X-ray emission from the following processes should be polarised
Measurement Technique
•Cyclotron
Anisotropic Thomson Scattering
•Synchrotron
•Non-Thermal Bremsstrahlung
•Scattering from non-spherical plasma
These objects should produce polarised X-ray radiation
•Accretion powered pulsars
Crab nebula is the only source for
which X-ray polarisation measurement
•Rotation powered pulsars
exists. This was made in 1976 !!
•Magnetars
Approved mission: GEMS
•Pulsar wind nebulae
•Non-thermal supernova remnants
•Black holes, micro-quasars and active galactic nuclei
39
Test Setup
CNC CONTROLLER
CNC ROTARY TABLE
DETECTORS
rotation axis
40
Test Results
Rishin et al. 2010
41
Engineering Model
The mechanical configuration
42
Development Status
Rishin et al. 2012
43
Thomson X-ray Polarimeter
Proposal submitted to ISRO
Included in ISRO’s 5 yr plan
Key features of the polarimeter
•Minimum detectable Polarisation of 2%
at 5 sigma level for a 50 mCrab source
•No of sources: 50
•Weight: 110 kg
•Data rate: 300 Mb per orbit
Collimator
Scatterer
Detectors
Spacecraft requirements
•Spinning platform/satellite, 0.5-5 rpm
•Very long exposures required, one week to one month
•Pointing accuracy required: 0.1 degree
•Equatorial orbit, less than 10 degree
•Altitude: 500—600 km
44
HXMT, SVOM, LOFT

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