Speaker
Description
During the hard and quiescent spectral states in X-ray binaries, a non-linear correlation is observed between radio and X-ray luminosities, providing a valuable tool to probe the connection between accretion and jet production. This relation was originally thought to define a single ‘standard’ correlation spanning several orders of magnitude in X-ray luminosity, and was extended to active galactic nuclei by including a mass term. However, subsequent studies have revealed numerous outliers that challenge the universality of the correlation. Most previous investigations of the radio:X-ray plane have combined observations from multiple radio and X-ray facilities, introducing significant systematic uncertainties associated with flux conversions between observing frequencies and differing instrumental systematics. These limitations reduce the diagnostic power of the plane and hinder efforts to identify the physical drivers of its observed diverse correlations. In contrast, we have compiled a homogeneous dataset from the five-year ThunderKAT and SwiftKAT programmes, comprising quasi-simultaneous MeerKAT and Swift/XRT observations of outbursting X-ray binaries. These data have been made publicly available through an interactive website. A key finding is the frequent detection of unresolved radio emission during the soft state, likely dominated by previously launched jet ejecta. Using these data, we have also constructed the largest homogeneous radio:X-ray plane for X-ray binaries to date. I will discuss the results of this study and the implications for our understanding of accretion flows and jet launching.