Name: Biplob Sarkar
Affiliation: Tezpur University
Conference ID : ASI2022_72
Title : Broad-band spectral and temporal characteristics of NS LMXB 4U1608-52 through AstroSat observations
Authors : Biplob Sarkar^1, Ankur Nath^1, Aru Beri^2 and Ranjeev Misra^3 (1) Department of Applied Sciences, Tezpur University, Napaam-784028, Tezpur, Assam, India (2) DST-INSPIRE Faculty, Indian Institute of Science Education and Research (IISER) Mohali, Punjab 140306, India (3) Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune 411 007, India
Abstract Type: Poster
Abstract Category : Extragalactic Astronomy
Abstract : We present the broadband results from the study of a neutron star low-mass X-ray binary 4U 1608-52. The source was observed for an exposure time of around 40 ks with AstroSat. The long-term MAXI (soft energy band) and Swift BAT (hard energy band) light curves reveals that the position of AstroSat observation for the source is deviated from the peak in both cases. This gives us a preliminary hint that the source was in the hard-intermediate state during the AstroSat observation period. Analysis of the Hardness Intensity diagram shows that there is a strong positive correlation between source intensity and hardness. Therefore, we perform flux-resolved spectroscopy on the data extracted from SXT, LAXPC 10 and LAXPC 20 counters. The X-ray continuum can be satisfactorily explained using an absorbed thermal Comptonized model together with a blackbody component, but residuals are observed around 6.4 keV, which indicates the presence of Fe-line emission characteristics. Our timing analysis reveals a positive correlation of the fractional r.m.s power with energy bands of increasing energies. We find significant evolution in the photon index with the X-ray flux whereas the electron temperature is found to remain approximately constant. We discuss the implication of our findings on the changes in accretion geometry of the source with the X-ray flux. References: Nath, A., Sarkar, B., Beri, A., Misra, R., 2022, under preparation.