title: An intermediate-mass black hole of over 500 solar masses in the galaxy ESO 243-49.
abstract: Ultraluminous X-ray sources are extragalactic objects located outside the nucleus of the host galaxy with bolometric luminosities exceeding 10(39) erg s(-1). These extreme luminosities-if the emission is isotropic and below the theoretical (Eddington) limit, where the radiation pressure is balanced by the gravitational pressure-imply the presence of an accreting black hole with a mass of approximately 10(2)-10(5) solar masses (M[symbol: see text]). The existence of such intermediate-mass black holes is in dispute, and though many candidates have been proposed, none are widely accepted as definitive. Here we report the detection of a variable X-ray source with a maximum 0.2-10 keV luminosity of up to 1.1 x 10(42) erg s(-1) in the edge-on spiral galaxy ESO 243-49, with an implied conservative lower limit for the mass of the black hole of approximately 500M[symbol: see text].
authors: Université de Toulouse, UPS, CESR, 9 Avenue du Colonel Roche, F-31028 Toulouse Cedex 9, France. saf28@star.le.ac.uk
authors: Sean A
authors: SA
authors: Farrell
authors: Natalie A
authors: NA
authors: Webb
authors: Didier
authors: D
authors: Barret
authors: Olivier
authors: O
authors: Godet
authors: Joana M
authors: JM
authors: Rodrigues