Soft-excess in ULX spectra: disc emission or wind absorption?
| dc.creator | Goncalves, A. C. | |
| dc.creator | Soria, R. | |
| dc.date | 2006-12-01 | |
| dc.date.accessioned | 2026-07-07T10:36:40Z | |
| dc.date.available | 2026-07-07T10:36:40Z | |
| dc.description | We assess the claim that Ultra-luminous X-ray sources (ULXs) host intermediate-mass black holes (BH) by comparing the cool disc-blackbody model with a range of other models, namelly a more complex physical model based on a power-law component slightly modified at various energies by smeared emission/absorption lines from highly-ionized gas. Our main conclusion is that the presence of a soft excess, or a soft deficit, depends entirely on the energy range to which we choose to fit the ``true'' power-law continuum; hence, we argue that those components should not be taken as evidence for accretion disc emission, nor used to infer BH masses. We speculate that bright ULXs could be in a spectral state similar to (or an extension of) the steep-power-law state of Galactic BH candidates, in which the disc is completely comptonized and not directly detectable, and the power-law emission may be modified by the surrounding, fast-moving, ionized gas. | |
| dc.description | 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). Compilation needs specific AIP .clo, .cls, .sty and .tex files (included along with the paper .tex file and figures) | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0612036 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0612036 | |
| dc.identifier | AIPConf.Proc.924:741-746,2007 | |
| dc.identifier | doi:10.1063/1.2774936 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/180130 | |
| dc.subject | Astrophysics | |
| dc.title | Soft-excess in ULX spectra: disc emission or wind absorption? | |
| dc.type | text |