The black hole transient MAXI J1348-630: evolution of the compact and transient jets during its 2019/2020 outburst

TL;DR

This study monitors the 2019/2020 outburst of MAXI J1348-630, revealing detailed evolution of its jets, including high proper motion ejecta and jet deceleration, providing insights into black hole jet behavior during outbursts.

Contribution

First detailed tracking of jet evolution and high proper motion ejecta in MAXI J1348-630 during its outburst, with constraints on jet speed, inclination, and interaction with the interstellar medium.

Findings

Detected and tracked compact and transient jets over 14 months.

Measured highest proper motion for black hole binary ejecta.

Observed jet deceleration suggesting a low-density cavity environment.

Abstract

We present the radio and X-ray monitoring campaign of the 2019/2020 outburst of MAXI J1348-630, a new black hole X-ray binary (XRB) discovered in 2019 January. We observed MAXI J1348-630 for $\sim$14 months in the radio band with MeerKAT and the Australia Telescope Compact Array (ATCA), and in the X-rays with MAXI and Swift/XRT. Throughout the outburst we detected and tracked the evolution of the compact and transient jets. Following the main outburst, the system underwent at least 4 hard-state-only re-flares, during which compact jets were again detected. For the major outburst, we observed the rise, quenching, and re-activation of the compact jets, as well as two single-sided discrete ejecta, launched $\sim$2 months apart and travelling away from the black hole. These ejecta displayed the highest proper motion ($\gtrsim$100 mas day$^{-1}$) ever measured for an accreting black hole binary. From the jet motion, we constrain the ejecta inclination and speed to be $\leq$46$^{\circ}$ and $\geq$0.69 $c$, and the opening angle and transverse expansion speed of the first component to be $\leq$6$^{\circ}$ and $\leq$0.05 $c$. We also infer that the first ejection happened at the hard-to-soft state transition, before a strong radio flare, while the second ejection was launched during a short excursion from the soft to the intermediate state. After traveling with constant speed, the first component underwent a strong deceleration, which was covered with unprecedented detail and suggested that MAXI J1348-630 could be located inside a low-density cavity in the interstellar medium, as already proposed for XTE J1550-564 and H1743-322.