National conference on REcent Trends in the study of Compact Objects (RETCO-V): Theory and Observation

Wideband spectral analysis of the brightest Black Hole X-ray Binary 4U 1543-47 in the 2021 Outburst

Apr 3, 2023, 5:35 PM

15m

Auditorium (Kodaikanal Solar Observatory)

Black Hole: Observations Black Hole: Observations

Speaker

Geethu Prabhakar (Indian Institute of Space Science and Technology, Trivandrum)

Description

4U 1543-47 is a galactic low-mass X-ray binary discovered in 1971. It has undergone five outbursts. The fifth outburst that happened in 2021 marks the source as the brightest X-ray binary source ever reported with a peak X-ray intensity of $\sim$11 Crab in 2-4 keV with MAXI/GSC. We aim for a comprehensive analysis of the wideband spectral characteristics of the source using NICER, NuSTAR and AstroSat Observations. We carried out phenomenological and reflection modelling using simultaneous reflection NICER-NuSTAR and AstroSat epochs. We found that the source was in HSS throughout, with a steep Γ due to a very small fraction (< 3%) of inverse-Comptonized photons. Reflection modelling reveals that the inclination of the system is between $\sim$32°-40°, disk possesses high ionization (log $\xi$ > 3) and overabundance of iron (3.6−10 A${}_{Fe\odot }$). We reported the presence of strong and dynamic absorption features in the spectra between $\sim$8-11 keV throughout the outburst. This detection is the first of its kind for X-ray binaries. In addition, there exists a neutral absorption edge feature in the spectrum. We studied the evolution of the equivalent width of both components and found that these components follow the same trend with a delay of typical viscous timescale of 10-15 days. In this presentation, I plan to discuss the physical origin of the observed absorption feature and the accretion dynamics of 4U 1543-47 during the 2021 outburst.