2003/03/03 by Luis C. Ho, Yuichi Terashima, Takashi Okajima · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/375042
published as Astrophys.J. 587 (2003) L35-L38 · To appear in ApJ (Letters). 4 pages
arxiv created 2003/03/03 · openalex publication_date 2003/03/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
The globular cluster M15 has recently been found to host a possible central black hole with a mass of ~2000 M ☉ . A deep, high-resolution Chandra image failed to detect the "nucleus" of the cluster in X-rays. The upper limit on the X-ray luminosity ( L X ≲ 5.6 × 10 32 ergs s -1 ) corresponds to a bolometric Eddington ratio of L bol / L Edd ≲ (2-4) × 10 -8 . Combining this limit with an estimate of the electron density of the intracluster ionized plasma derived from pulsar dispersion measures, we show that the radiative efficiency of the accretion flow, if it accretes at the Bondi rate, must be much lower than that of a standard optically thick, geometrically thin disk.