paper

Wideband Study of the Brightest Black Hole X-ray Binary 4U 1543-47 in the 2021 Outburst: Signature of Disk-Wind Regulated Accretion

arXiv:2301.13711 · doi:10.1093/mnras/stad080

Abstract

A comprehensive wideband spectral analysis of the brightest black hole X-ray binary 4U during its 2021 outburst is carried out for the first time using NICER, NuSTAR, and AstroSat observations by phenomenological and reflection modelling. The source attains a super-Eddington peak luminosity and remains in the soft state, with a small fraction () of the inverse-Comptonized photons. The spectral modelling reveals a steep photon index () and relatively high inner disk temperature ( keV). The line-of-sight column density varies between () cm. Reflection modelling using the RELXILL model suggests that 4U is a low-inclination system (). The accretion disk is highly ionized (log > 3) and has super solar abundance (3.610 ) over the entire period of study. We detected a prominent dynamic absorption feature between keV in the spectra throughout the outburst. This detection is the first of its kind for X-ray binaries. We infer that the absorption of the primary X-ray photons by the highly ionized, fast-moving disk-winds can produce the observed absorption feature. The phenomenological spectral modelling also shows the presence of a neutral absorption feature keV, and both ionized and neutral absorption components follow each other with a delay of a typical viscous timescale of days.

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