An Intermediate-mass Black Hole of Over 500 Solar Masses in the Galaxy ESO 243-49

Understand

Ultra-luminous X-ray sources are extragalactic objects located outside the nucleus of the host galaxy with bolometric luminosities >10^39 erg s^-1.

• These extreme luminosities - if the emission is isotropic and below the theoretical (i.e.
• Eddington) limit, where the radiation pressure is balanced by the gravitational pressure - imply the presence of an accreting black hole with a mass of ~10^2-10^5 times that of the Sun.
• The existence of such intermediate mass black holes is in dispute, and though many candidates have been proposed, none are widely accepted as definitive.