Establishing a Connection between the Jet and the Corona in Black Hole Low-mass X-Ray Binaries

Abstract Black hole low-mass X-ray binaries (LMXBs) undergo outbursts, during which their brightness increases greatly for timescales of months. The X-ray accretion and radio jet properties change dramatically throughout an outburst in a broadly consistent way between sources. Changes to the accretion flow and the corona are evident through X-ray spectral variations, while the jet’s evolution produces changes in the radio. Typically, high-energy emission from the corona initially dominates the X-ray spectrum, and quasi-steady compact jets are observed in the radio. As the outburst progresses, emission from the corona fades and is superseded by lower-energy X-ray accretion disk emission. During this transition, the compact jets are quenched and discrete ejecta, called transient jets, are launched. The concurrence of the corona’s weakening and the jet’s transition from compact to transient implies a connection, but the precise relationship has not been established. Motivated by this, we aim to investigate the corona–jet connection. We perform spectral modeling in the hard and soft X-ray, utilizing NuSTAR, NICER, and Swift X-Ray Telescope observations to track the evolving X-ray corona for three LMXBs: MAXI J1348−630, MAXI J1535−571, and MAXI J1820+070. We use prior work to mark the presence of compact jets and the dates of discrete jet ejections. We find a clear connection between the evolution of the corona and the jet: across all three sources an increase in the distance of the corona from the black hole occurs near the time that the compact jet is quenched, and the transient jet is launched.