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

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 \(1^{st}\) to September \(26^{th}\), 2021. The first three observations were performed with an offset of 40 arcmin with A...

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Bibliographic Details
Published in:arXiv.org 2023-07
Main Authors: Husain, Nazma, Bhargava, Yash, Garg, Akash, Mudambi, Sneha Prakash, Misra, Ranjeev, Sen, Somasri
Format: Article
Language:English
Subjects:
Evolution
Outbursts
Relativistic effects
Spectrum analysis
Online Access:Get full text
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Summary: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 \(1^{st}\) to September \(26^{th}\), 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 \(\geq2.5\)) 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.
ISSN:2331-8422
DOI:10.48550/arxiv.2307.10831