Reflection features in the hard state brightening of 4U 1543-475
ATel #15261; Guglielmo Mastroserio (Caltech), Javier Garcia (Catech), Riley Connors (Caltech), Jingyi Wang (MIT), Erin Kara (MIT), Karl Foster (Caltech), Brian Grefenstette (Catech)
on 4 Mar 2022; 02:17 UT
Credential Certification: Guglielmo Mastroserio (gullik@caltech.edu)
The black hole binary 4U 1543-475 started an outburst in June 2021 (ATels #
14701, #
14708) after several years in quiescence. NuSTAR and NICER (ATel #
14725) observed the source in the bright soft state with a peak luminosity of ~5.4 Crab (2-10 keV). The source constantly declined for the next few months reaching back to the quiescence state.
On 2022 Feb 15 4U 1543-475 had a re-brightening detected in MAXI/GSC. Swift/BAT recovered from the safe mode status only a few days later and it detected the source on 2022 Feb 18. NICER observed the source starting on 2022 Feb 23 (ATel #
15255) until 2022 Mar 1. All these X-ray telescopes have observed a gradual decline of the source flux since the detection of the re-brightening. The source was also detected at Radio (ATel #
15157), Optical and IR (ATel #
15254) wavelength.
We report on one NuSTAR observation that was performed on 2022 Feb 28 with a total exposure of 37 ks. The net count rate in both FPMs is ~8 cts/s. The inferred flux from an absorbed power-law model (Wilms et al. 2000 abundances and column density fixed to 4.0 E21) is 2.85 +/-0.01 E-10 erg cm
s
(2-10 keV) which corresponds to ~10 mCrab. The photon index of a preliminary power-law fit is 1.65 +/- 0.01 that confirms the source is in the hard state and the residuals show strong reflection signatures (see attached plot).
4U 1543-475 flux energy spectrum residuals
