MeerKAT and Swift/XRT detection of MAXI J1348-630

ATel #13467; Francesco Carotenuto (CEA-Saclay), Stephane Corbel (CEA-Saclay), Rob Fender (Oxford, UCT), Patrick Woudt (UCT), James Miller-Jones (ICRAR/Curtin), on behalf of the ThunderKAT collaboration
on 11 Feb 2020; 16:41 UT
Credential Certification: Evangelia Tremou (evangelia.tremou@cea.fr)

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A re-brightening of the black hole candidate MAXI J1348-630 has been reported at optical wavelengths by the LCO from observations starting on January 24 2020 (ATel #13451), and the source was subsequently detected in X-rays by MAXI/GSC (ATel #13459) and NICER (ATel #13465), suggesting the occurrence of a new outburst, now entering a decay phase.

We have been monitoring the source since the start of the discovery outburst in January 2019 with the MeerKAT radio-interferometer (ATel #12497), as part of the ThunderKAT Large Survey Programme (Fender et al. 2017, arXiv:1711.04132).

Following the recent alerts, we observed the target field on February 08 2020 (MJD 58887.185) starting at 04:19 UT for 15 minutes with 62 antennas, at a central frequency of 1.28 GHz and with a total bandwidth of 860 MHz. MAXI J1348-630 is detected at a flux density of 0.38 +/- 0.03 mJy, with the radio emission being consistent with the known core position. This is the first radio detection of the core with MeerKAT in the last two months, since no emission from the core was detected after December 07 2019.

MAXI J1348-630 is also clearly detected in a Swift/XRT observation taken on February 10 2020 (MJD 58889.52), displaying a spectrum which is well-fitted by an absorbed power-law with a photon index of 1.8 +/- 0.2 and a total unabsorbed flux of ~1e-10 erg/cm^2/s in the 1-10 keV energy range. This is compatible with the source currently being in the hard state and implies that the radio emission is likely produced by a re-ignition of the self-absorbed compact jets. We encourage multi-wavelength follow-up observations.

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 observation 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 scheduling and carrying out these observations. The MeerKAT telescope is operated by SARAO, which is a facility of the National Research Foundation, and agency of the Department of Science and Innovation.