Soft-excess in ULX spectra: the chilled-disk scenario
Abstract
Soft X-ray spectra of ULXs show small deviations from a power-law model, that can be attributed to reprocessing in a fast, ionized outflow, or to thermal emission from a cool disk. If it is thermal emission, the cool peak temperature can be explained by an inner disk that radiates only a small fraction of the gravitational power, transferring the rest to an upscattering medium which is then responsible for the dominant power-law component. This scenario does not require intermediate-mass black holes: we use a phenomenological model to show that the observed X-ray luminosities and spectra of ULXs are consistent with typical masses ~ 50-100 Msun.
Keywords
Cite
@article{arxiv.astro-ph/0611153,
title = {Soft-excess in ULX spectra: the chilled-disk scenario},
author = {Roberto Soria and Anabela Goncalves and Zdenka Kuncic},
journal= {arXiv preprint arXiv:astro-ph/0611153},
year = {2008}
}
Comments
To appear in the proceedings of "The Multicoloured Landscape of Compact Objects and their Explosive Progenitors: Theory vs Observations", Cefalu', Sicily, June 11-24, 2006 (AIP)