Ultraluminous X-ray source
= Ultraluminous X-ray source
{title2=ULX}
An <ultraluminous X-ray source> is an apparently off-nuclear compact X-ray source with inferred isotropic <luminosity> above roughly $10^{32}$ W. <Luminosity> alone does not establish an <intermediate-mass black hole>: supercritical accretion, beaming and magnetized neutron-star accretion can also produce large apparent <luminosities>. Spatial association, spectra, timing and dynamical constraints help distinguish models.