Neutron star observations in hard X-rays

1. Missions • Ginga 2-37 keV • RXTE 2-25, 20-100, keV • Integral/Swift 15-150 keV • BATSE/GBM 15/7-50 keV • Beppo-SAX 0.1-100 keV • Suzaku 0.5-150 keV • Nu-Star 5-80 keV • Astro-H 0.5-200 keV • Astrosat 0.5-150 keV • POLIX 5-30 keV • LOFT 2-50 keV Neutron star observations in hard X-rays Hard X-rays are emitted by Accretion powered pulsars Magnetars Young rotation powered pulsars

2. Thanks to Sushan

3. Magnetars1013-15 Gauss (SGR, AXP) • Short lived evolutionary track of the magnetarsafter 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

4. 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. Magnetars

5. Magnetar hard X-ray emission Kuiper et al. 2008

6. Magnetar hard X-ray emission Kuiper et al. 2008

7. 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 magnetarmodels Magnetars

8. 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. Young Neutron Stars

9. Rotation Powered PulsarsHard X-ray emission Kuiper and Hermsen 2009, 2010

10. Energy dependent pulse profiles Kuiper and Hermsen 2010

11. Spin-evolution, Quasi-period Oscillations Orbital evolution, orbital glitches Broad band spectrum Accretion Powered Pulsars 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

12. Energy dependent pulse profiles Sasaki et al. 2010

13. Luminosity dependent pulse profiles Parmar et al. 1989

14. 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 XTE J1710-281 EXO 0748-676 4U 1822-37 Her X-1 Her X-1

15. Cycltron linesLuminosity dependencePulse phase dependence

16. Dips in Pulse Profiles : Partial Covering Absorption Devasia, PhD thesis 2012

17. Dips in Pulse Profiles : Partial Covering Absorption Galloway et al. 2001

18. NuSTAR

20. 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 NuStar

21. ASTRO-H

22. ASTRO-H c

23. 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 Astro-H

24. ASTROSAT

25. IXAE Indian X-ray Astronomy Instrument Onboard IRS-P3, 1996

27. Large Area X-ray Proportional Counter

28. ASTROSAT Ground Trace

29. Pulsar Cyclotron lines

30. Cyclotron lines studies with LAXPC ChandreyeeMaitra 2012

31. Thermonuclear X-ray Burst Reprocessing

32. Reprocessing in EXO 0748-676: XMM-Newton Observations

33. Hard X-ray Quasi Periodic Oscillations

34. Good for moderate/bright sources time/phase resolved studies Multi-wavelength observations Stable background Astrosat

35. X-ray Polarimetry

36. Polarised X-rays

37. Accreting X-ray Pulsars Image: NASA Meszaros et al. 1988

38. POLIX

39. Measurement Technique Anisotropic Thomson Scattering X-ray Polarimeter Polarisation is unexplored in High Energy Astrophysics X-ray emission from the following processes should be polarised Cyclotron Synchrotron Non-Thermal Bremsstrahlung Scattering from non-spherical plasma These objects should produce polarised X-ray radiation Accretion powered pulsars Rotation powered pulsars Magnetars Pulsar wind nebulae Non-thermal supernova remnants Black holes, micro-quasars and active galactic nuclei Crab nebula is the only source for which X-ray polarisation measurement exists. This was made in 1976 !! Approved mission: GEMS

40. Test Setup

41. Test Results Rishin et al. 2010

42. Engineering ModelThe mechanical configuration

43. Development Status Rishin et al. 2012

44. Collimator Scatterer Detectors 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 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

45. HXMT, SVOM, LOFT