Probing the soft state evolution of 4U 1543-47 during its 2021 outburst using AstroSat

Nazma Husain; Yash Bhargava; Akash Garg; Sneha Prakash Mudambi; Ranjeev Misra; Somasri Sen

doi:10.1093/mnras/stad2204

paper

Probing the soft state evolution of 4U 1543-47 during its 2021 outburst using AstroSat

arXiv:2307.10831 · doi:10.1093/mnras/stad2204

Abstract

4U 1543-47 underwent its brightest outburst in 2021 after two decades of inactivity. During its decay phase, AstroSat conducted nine observations of the source spanning from July $1^{s t}$ to September $2 6^{t h}$ , 2021. The first three observations were performed with an offset of 40 arcmin with AstroSat/LAXPC, while the remaining six were on-axis observations. In this report, we present a comprehensive spectral analysis of the source as it was in the High/Soft state during the entire observation period. The source exhibited a disk-dominated spectra with a weak high-energy tail (power-law index $\geq 2.5$ ) and a high inner disk temperature ( $\sim$ 0.84 keV). Modelling the disk continuum with non-relativistic and relativistic models, we find inner radius to be significantly truncated at $>$ $10 R_{g}$ . Alternatively, to model the spectral evolution with the assumption that the inner disk is at the ISCO, it is necessary to introduce variation in the spectral hardening in the range $\sim$ 1.5-1.9.

Accepted for publication in MNRAS, 10 pages, 7 figures and 2 tables

Probing the soft state evolution of 4U 1543-47 during its 2021 outburst using AstroSat

Abstract

References in corpus (12)