XTE J1118+480: Clues on the Nature of the Accretion Flow from the Optical Variability

Abstract

We show how the simultaneous presence of a strong quasi periodic oscillation (QPO) of period of about 10 seconds in the optical and X-ray lightcurves of the X-ray transient XTE J1118+480 can be used to obtain information about the nature of the accretion flow around the source. The unusually high optical-to-X-ray flux ratio and the QPO observed simultaneously in both energy bands suggest that a significant fraction of the optical flux might originate close to the central source, where most of the X-rays are produced and be indicative of a magnetically dominated corona. We also show how the temporal evolution of the QPO can provide us with information on both the inner radius and the viscous properties of the optically thick accretion disc.

arXiv comment4 pages, 1 figure. To be published in `Proceedings of the Third Microquasar Workshop: Granada Workshop on galactic relativistic jet sources', Eds: A. J. Castro-Tirado, J. Greiner and J. M. Paredes, Astrophysics and Space Science, in press

References in corpus (5)

• Correlations in the QPO Frequencies of Low Mass X-Ray Binaries and the Relativistic Precession Model
• Correlations in Quasi-Periodic Oscillation and Noise Frequencies Among Neutron-Star and Black-Hole X-ray Binaries
• On the interpretation of the multicolour disc model for black hole candidates
• The X-ray transient XTE J1118+480: Multiwavelength observations of a low-state mini-outburst
• Magnetic flares and the optical variability of the X-ray transient XTE J1118+480

Cited by in corpus (1)

• The 2005 outburst of the halo black hole X-ray transient XTE J1118+480