Radio brightening of the transient black hole 4U 1543-47 as seen with MeerKAT
ATel #14878; Xian Zhang, Wenfei Yu (Shanghai Astronomical Observatory), Rob Fender (University of Oxford), Patrick Woudt (University of Cape Town), James Miller-Jones (Curtin University), Sara Motta (INAF-OAB & University of Oxford), on behalf of the ThunderKAT collaboration
on 27 Aug 2021; 16:15 UT
Credential Certification: Wenfei Yu (wenfei@shao.ac.cn)
Subjects: Radio, Black Hole, Transient
After ~ 17 years of quiescence, the black hole X-ray binary 4U 1543-47 was found in an X-ray outburst by MAXI/GSC on June 11, 2021 (ATel #14701). It probably went through a very fast hard-to-soft spectral state transition in the same day. Since then, the source has been residing in the soft spectral state (ATel #14701, #14708, #14725, #14749).
As part of the ThunderKAT Large Survey Programme (Fender et al. 2017, arXiv:1711.04132), we started to monitor 4U 1543-47 on a weekly basis with the MeerKAT telescope since June 19. Each observation consists of an on-source exposure time of ~ 15 minutes. J1939-6342 has been used as the bandpass and flux density calibrator while J1501-3918 as the phase calibrator throughout our monitoring. On August 22, 4U 1543-47 was detected with a flux density of 14.45 +/- 0.06 mJy at 1.284GHz based on our preliminary measurements. This was the first detection of radio emission from this source after nearly one month of non-detection since July 26. This indicates a radio brightening of 4U 1543-47. We encourage multi-wavelength follow-up observations of the source.
ThunderKAT will run for 5 years and targets X-ray binaries, Cataclysmic Variables, Supernovae and Gamma-Ray Bursts. As part of this programme we perform weekly monitoring observations of all bright, active, southern hemisphere X-ray binaries in the radio band. For further information on this programme please contact Rob Fender and/or Patrick Woudt.
We thank the staff at the South African Radio Astronomy Observatory (SARAO) for their rapid scheduling of these observations. The MeerKAT telescope is operated by SARAO, which is a facility of the National Research Foundation, an agency of the Department of Science and Technology.
