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

• Published in: Astrophysical journal. Letters Vol. 801; no. 1; pp. L4 - 4
• Main Authors: Lasota, Jean-Pierre, King, Andrew R., Dubus, Guillaume
• Format: Journal Article
• Language: English
• Published: United States The American Astronomical Society 01.03.2015; Bristol : IOP Publishing
• Subjects: ACCRETION DISKS; accretion, accretion disks; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BINARY STARS; black hole physics; BLACK HOLES; COSMIC X-RAY SOURCES; Disks; GALAXIES; Grounds; Instability; LUMINOSITY; MASS; Pictures; Sciences of the Universe; SELF-IRRADIATION; SOFT X RADIATION; Stability; TRANSIENTS; X-ray sources; X-rays; accretion; black hole physics; Astrophysics - High Energy Astrophysical Phenomena; accretion disks
• ISSN: 2041-8205; 2041-8213; 2041-8213
• DOI: 10.1088/2041-8205/801/1/L4

ABSTRACT 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 & 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.