National conference on REcent Trends in the study of Compact Objects (RETCO-V): Theory and Observation

Broad-band mHz QPOs and spectral study of LMC X-4 with AstroSat

Apr 4, 2023, 3:05 PM

15m

Auditorium (Kodaikanal Solar Observatory)

Neutron Stars Neutron Stars

Speaker

Rahul Sharma (Raman Research Institute)

Description

LMC X-4 is a highly luminous and eclipsing high-mass X-ray binary pulsar which is known to exhibit variations in X-ray flux over a wide range of time scales. The Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) instruments onboard the AstroSat observed the source in August 2016. The source was found to emit an X-ray luminosity of $\sim 2\times {10}^{38}$ erg s${}^{-1}$ in the energy range of 0.5-25 keV. The power density spectrum showed the presence of coherent pulsations at 13.5 s along with a $\sim 26$ mHz quasi-periodic oscillation feature. From the joint analysis of the SXT and LAXPC spectral data, the 0.5-25 keV spectra were found to be comprised of an absorbed high-energy cut-off power law with a photon index of ~0.8 and cut-off at ~16 keV, a soft thermal component with $k{T}_{BB}\sim 0.14$ keV, and emission lines due to Fe K$\alpha$, Ne IX, and Ne X. We will discuss the implications of these results.