LEDA 6390 , the SIMBAD biblio

Using the Chandra Source Catalog 2.0 and a newly compiled catalogue of galaxies in the local Universe, we deliver a census of ultraluminous X-ray source (ULX) populations in nearby galaxies. We find 629 ULX candidates in 309 galaxies with distance smaller than 40 Mpc. The foreground/background contamination is ∼20 per cent. The ULX populations in bona fide star-forming galaxies scale on average with star formation rate and stellar mass (M_*) such that the number of ULXs per galaxy is 0.45^+0.06_–0.09×S/FR M_☉yr-1^+3.3+3.8^_–3.2×\fracM_*_ M_☉. The scaling depends strongly on the morphological type. This analysis shows that early spiral galaxies contain an additional population of ULXs that scales with M_*. We also confirm the strong anticorrelation of the ULX rate with the host galaxy's metallicity. In the case of early-type galaxies, we find that there is a non-linear dependence of the number of ULXs with M_*, which is interpreted as the result of star formation history differences. Taking into account age and metallicity effects, we find that the predictions from X-ray binary population synthesis models are consistent with the observed ULX rates in early-type galaxies, as well as spiral/irregular galaxies.