Authors: Cosimo Bambi, Enrico Barausse
Date: 24 Aug 2011
Abstract: The $5 - 20 M_\odot$ dark objects in X-ray binary systems and the $10ˆ5 - 10ˆ9 M_\odot$ dark objects in galactic nuclei are currently thought to be the Kerr black holes predicted by General Relativity. However, direct observational evidence for this identification is still elusive, and the only viable approach to confirm the Kerr black hole hypothesis is to explore and rule out any other possibility. Here we investigate the final stages of the accretion process onto generic compact objects. While for Kerr black holes and for more oblate bodies the accreting gas reaches the innermost stable circular orbit (ISCO) and plunges into the compact object, we find that for more prolate bodies several scenarios are possible, depending on the spacetime geometry. In particular, we find examples in which the gas reaches the ISCO, but then gets trapped between the ISCO and the compact object. In this situation, accretion onto the compact object is possible only if the gas loses additional angular momentum, forming torus-like structures inside the ISCO.
© M. Vallisneri 2012 — last modified on 2010/01/29
Tantum in modicis, quantum in maximis