Astronomy and Astrophysics Seminars

Study of Black Hole Binaries using Space Based X-ray Astronomy Satellites.

by Dr. Md Shah Alam (IUCAA, Pune)

Tuesday, May 22, 2018 from to (Asia/Kolkata)
at DAA SEMINAR ROOM ( A269 )
TIFR
Description
We studied One unconfirmed black hole X-ray binary IGR J17497-2821, and two confirmed black hole binaries: LMC X-1 and Cyg X-1, using X-ray astronomy satellites like AstroSat, RXTE, Suzaku, and XMM-Newton. The models were used to understand the structure of accretion disk and corona, and to explain the strong gravitational effect. Asymmetric broadening in iron line profile, observed in the energy spectrum of BHB systems, is due to the massive gravity near the black hole. We used this line profile to study the properties of black hole like spin, size, etc. We examined the variation of the size and strength, of accretion disk and corona, with time. In some cases, accretion disk was found to be extended very near to the black hole whereas in some cases, it was truncated far away. To check the periodicity in the lightcurve, we generated power density spectrum (PDS) using Fourier transform techniques. We tried to relate the properties of the PDS to the energy spectrum. We discovered the quasi-periodic oscillation (QPO) at ∼ 30 mHz, in the power density spectrum of LMC X-1 in the high/soft state. In this system, we found that both QPO and broad iron line were present simultaneously. We also found that strength of QPO was very weak in low energy band (0.6-2 keV). We tried to correlate the other temporal properties of the PDS like integrated rms, break frequencies, etc., with spectral properties. We studied the absorbing material between accretion disk and companion star in Cygnus X-1 using AstroSat data. We found ten absorption dips in the lightcurve. Most of the absorption dips were found in zero binary phase. We also studied the broadband energy spectrum of Cygnus X-1 using SXT, LAXPC, and CZTI and found Break energy ~10 keV, consistent with earlier observations.