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Title: X-RAY TRANSIENTS: HYPER- OR HYPO-LUMINOUS?

The disk instability picture gives a plausible explanation for the behavior of soft X-ray transient systems if self-irradiation of the disk is included. We show that there is a simple relation between the peak luminosity (at the start of an outburst) and the decay timescale. We use this relation to place constraints on systems assumed to undergo disk instabilities. The observable X-ray populations of elliptical galaxies must largely consist of long-lived transients, as deduced on different grounds by Piro and Bildsten (2002). The strongly varying X-ray source HLX-1 in the galaxy ESO 243-49 can be modeled as disk instability of a highly super-Eddington stellar-mass binary similar to SS 433. A fit to the disk instability picture is not possible with an intermediate-mass black hole model for HLX-1. Other recently identified super-Eddington ULXs might be subject to disk instability.
Authors:
;  [1] ;  [2]
  1. CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis Bd Arago, F-75014 Paris (France)
  2. Theoretical Astrophysics Group, University of Leicester, Leicester LE1 7RH (United Kingdom)
Publication Date:
OSTI Identifier:
22518816
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 801; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BINARY STARS; BLACK HOLES; COSMIC X-RAY SOURCES; GALAXIES; LUMINOSITY; MASS; SELF-IRRADIATION; SOFT X RADIATION; TRANSIENTS