Deciphering the nature of two IMBH candidates

Performing a search for Hyper Luminous X-ray sources (HLX) in thecatalog of Swift-XRT sources 1SXPS, we have discovered a few dozen HLXcandidates. Here we propose to observe two previously unknown brightHLX sources from our sample that appear to be good intermediate-massblack hole (IMBH) candidates. We request two modest XMM-Newtonobservations in order to accurately constrain the spectral nature ofthe two candidates and explore their variability, in order to determinetheir nature. Identifying new IMBHs will help our understanding of theformation and growth of supermassive black holes as IMBH are expectedto be the building bricks of these more massive BHs.