Abstract Details

Name: Sneha Prakash Mudambi
Affiliation: CHRIST(Deemed to be University)
Conference ID: ASI2021_129
Title : Spectral characteristics of the black hole X-ray binary 4U 1957+115 using AstroSat and SWIFT
Authors and Co-Authors : S.P. Mudambi (CHRIST(Deemed to be University), Bengaluru), S.B. Gudennavar (CHRIST(Deemed to be University), Bengaluru), R. Misra (Inter-University Center for Astronomy and Astrophysics, Pune) and S.G. Bubbly (CHRIST(Deemed to be University), Bengaluru)
Abstract Type : Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : 4U 1957+115, a persistently active black hole X-ray binary, has always been observed in the soft state since its discovery in 1973. Although the source has been studied in Optical and X-rays by most of the leading missions, precise measurements on the black hole mass and distance are yet to be achieved. In this work, we have carried out broadband (0.3-20.0 keV) spectral studies of the source using archival data from AstroSat. Modelling the combined spectra with a multicolor blackbody emission (diskbb) and a Comptonization component (simpl) revealed the presence of a standard accretion disc with a relatively high inner temperature (kTin = 1.37-1.64 keV) close to the black hole (Ndisk~8.83). Asymptotic power-law index (Gamma ~2.5) indicated that the source was in the high soft state. The best fit values of absorption column density (0.14x1022 cm-1) indicated the presence of a low absorption column in the line of sight of the source. Fitting the thermal disc emission with a relativistic model (kerrbb) for different combinations of mass and distance revealed that the system probably hosts a maximally spinning black hole. Furthermore, we carried out joint spectral fitting of SWIFT and AstroSat data for one of the Epochs using the same model combinations described above and found a good agreement between the results of joint SWIFT+AstroSat data analysis and AstroSat data analysis which in turn agrees with the previous results.