English

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

High Energy Astrophysical Phenomena 2023-08-02 v2

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 1st1^{st} to September 26th26^{th}, 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 2.5\geq2.5) and a high inner disk temperature (\sim0.84 keV). Modelling the disk continuum with non-relativistic and relativistic models, we find inner radius to be significantly truncated at >>10 Rg10~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 \sim1.5-1.9.

Keywords

Cite

@article{arxiv.2307.10831,
  title  = {Probing the soft state evolution of 4U 1543-47 during its 2021 outburst using AstroSat},
  author = {Nazma Husain and Yash Bhargava and Akash Garg and Sneha Prakash Mudambi and Ranjeev Misra and Somasri Sen},
  journal= {arXiv preprint arXiv:2307.10831},
  year   = {2023}
}

Comments

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