Presentation #110.86 in the session “Stellar/Compact (Poster)”.
Ultraluminous X-ray sources (ULXs) are the most extreme members of the X-ray binary population, and are now broadly understood to represent the best local examples of highly super-Eddington accretion. Studying the accretion physics at play in these sources may be key to understanding the rapid assembly of supermassive black holes in the early universe, and some may even have evolutionary links to the (large) compact object mergers now regularly being seen via gravitational waves. We have recently published a new, multi-mission catalogue of ULX candidates, based on recent data releases from each of the XMM-Newton, Swift and Chandra observatories (the 4XMM-DR10, 2SXPS and CSC2 catalogues, respectively). This has been compiled by cross-correlating each of these X-ray archives with a large sample of galaxies primarily drawn from the HyperLEDA archive. Significant efforts have been made to clean the sample of known non-ULX contaminants (e.g. foreground stars, background AGN, supernovae), and also to identify ULX candidates that are common to the different X-ray catalogues utilized, allowing us to produce a combined ‘master’ list of unique sources. Our final sample contains 1843 ULX candidates associated with 951 different host galaxies, making it the largest ULX catalogue compiled to date. Of these, 689 sources are catalogued as ULX candidates for the first time. I will discuss the key details of this new catalogue, which will be a valuable resource for planning future observations of ULXs — both with our current and future X-ray facilities — to further improve our understanding of this enigmatic population.