SWIFT J1644+57: An ultra-luminous X-ray event

Abstract

The photon spectral energy distribution of the powerful transient Sw J1644+57 resembles those of the brightest ultra-luminous X-ray sources (ULXs). The transient nature of Sw J1644+57 is likely the result of a tidal disruption of a star by a supermassive black hole. The stellar disk generates accretion power at super-Eddington rates and the observational properties of Sw J1644+57 indicate - in analogy with ULXs - that the accretion flow maintains a high level of radiative efficiency with a corresponding super-Eddington luminosity. Due to its similarity to ULXs, this powerful transient may be thought of as an ultra-luminous X-ray event (ULX-E). Observational tests for this ULX-E model are proposed as well. © © 2012. The American Astronomical Society. All rights reserved.