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

• DOI: 10.1093/mnras/stad2204
• Publication Date: 2023-07-25T21:40:48Z
• Authors: Nazma Husain; Yash Bhargava; Akash Garg; Sneha Prakash Mud...; Ranjeev Misra; Somasri Sen
• Keywords: High Energy Astrophysical Phenomena (astro-ph.HE); 13. Climate action; FOS: Physical sciences; Astrophysics - High Energy Astrophysical Phenomena

4U 1543-47 underwent its brightest outburst in 2021 after two decades of inactivity. During decay phase, AstroSat conducted nine observations the source spanning from July $1^{st}$ to September $26^{th}$, 2021. The first three were performed with an offset 40 arcmin AstroSat/LAXPC, while remaining six on-axis observations. In this report, we present a comprehensive spectral analysis as it was High/Soft state during entire observation period. exhibited disk-dominated spectra weak high-energy tail (power-law index $\geq2.5$) and high inner disk temperature ($\sim$0.84 keV). Modelling continuum non-relativistic relativistic models, find radius be significantly truncated at $>$$10~R_g$. Alternatively, model evolution assumption that is ISCO, necessary introduce variation hardening range $\sim$1.5-1.9.