MeerKAT radio detection of MAXI J1820-222 following its hard state
ATel #16025; Thomas Russell (INAF-IASF Palermo), Andrew Hughes (U. Alberta), Francesco Carotenuto, Rob Fender, Katie Savard (Oxford), Patrick Woudt (U. Cape Town), James Miller-Jones Curtin), on behalf of the ThunderKAT collaboration
on 3 May 2023; 13:54 UT
Credential Certification: Thomas Russell (thomas.russell@inaf.it)
Subjects: Radio, Black Hole, Transient
MAXI J1810-222 is a black hole candidate X-ray binary that has been in outburst since 2018 November (ATel #12254), during which it has shown a number of transitions between the hard and soft X-ray state (Russell et al. 2022). Following recent reports of the source within the hard X-ray spectral state (ATel #16016), we observed MAXI J1810-222 with the MeerKAT radio telescope as part of the ThunderKAT Large Survey Programme (Fender et al. 2017). Observations were carried out at a central frequency of 1.28 GHz, with a total bandwidth of 860 MHz. We used PKS J1939-6342 for flux and bandpass calibration, and J1833-2103 for complex gain calibration.
MAXI J1810-222 was observed for 15 minutes on 2023-04-30 between 02:37:15 and 02:52:19 UTC (MJD 60064.114 +/- 0.005). We detect radio emission coincident with the known source position. Fitting for a point source in the image plane, we measure a flux density of 330 +/- 20 μJy (at 1.28 GHz). This radio flux density is consistent with previous observations of this source in its hard X-ray state (Russell et al. 2022).
Further radio monitoring is planned. Multiwavelength follow-up is encouraged.
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.
References:
Fender et al. 2017, arXiv:1711.04132
Russell et al. 2022, MNRAS, 513, 6196, arXiv:2205.05721
