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arXiv · 2407.15618

Spectro-temporal investigation of the black hole X-ray transient 4U 1543-475 during the 2021 outburst

Biki Ram·Manoneeta Chakraborty·Unnati Kashyap
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Abstract

We report a detailed spectro-temporal analysis of the black hole (BH) low mass X-ray binary (LMXB) 4U 1543-475 during its 2021 outburst using the data from LAXPC (Large Area X-ray Proportional Counters) and SXT (Soft X-ray Telescope) instrument on board AstroSat. We investigate the energy and frequency dependency of the source variability to probe the origin of the disc/coronal fluctuations. Following the state transition (from soft to intermediate state), the emergence of a band-limited noise (BLN) component is observed along with the power law noise (PLN) when the disk is recovering from a sudden decrease in the inner disk radius. A possible correlation between the low-frequency variability amplitude (RMS) and the covering fraction of the non-thermal component is detected. During the final AstroSat observation, a flip-flop phenomenon is reported, where rapid variation in RMS occurs in concurrence with sudden flux transition. An indication of the evolution of inner disk temperature along with a significant change in thermal flux was observed during the flip-flop phase, arguing for a disk instability-driven origin for this phenomenon. Our results suggest that the long-term variability evolution is primarily affected by the coronal changes, whereas the disk behavior governs the short-term variability evolution.

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Biki Ram, Manoneeta Chakraborty, Unnati Kashyap. 2024-07-22. Spectro-temporal investigation of the black hole X-ray transient 4U 1543-475 during the 2021 outburst. https://arxiv.org/abs/2407.15618

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