Jet ejection events from the intermediate mass black hole ESO243-49 HLX-1

Ultraluminous X-ray sources (ULXs) are variable off-nuclear extragalactic X-ray sources with luminosities greatly exceeding the Eddington luminosity of a 20-Msun compact object, assuming isotropic emission. ULXs are binary systems containing a compact object that is either a stellar-mass black hole (StMBH) with beamed or super-Eddington emission; or an intermediate-mass black hole (IMBH). Jets have been observed from StMBHs as well as from supermassive black holes (SMBHs). Jets should also be produced by IMBHs, although evidence for this third class of black hole has until recently been weak. We report the radio detection of jet ejection events during the transition from hard to soft states of the best IMBH candidate ESO243-49 HLX-1. We show that despite the very diverse nature of ULXs, some might can bridge the gap between StMHBs and SMBHs.