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- Title
Ultrafast outflows in ultraluminous X-ray sources.
- Authors
Pinto, C.; Fabian, A.; Middleton, M.; Walton, D.
- Abstract
Ultraluminous X-ray sources (ULXs) are bright extragalactic sources with X-ray luminosities above 1039 erg s-1 powered by accretion onto compact objects. According to the first studies performed with XMM-Newton, ULXs seemed to be excellent candidates to host intermediate-mass black holes (102--4M☉). However, in the last years, the interpretation of super-Eddington accretion onto stellar-mass black holes or neutron stars for most ULXs has gained a strong consensus. One critical missing piece to confirm the super-Eddington scenario was the direct detection of the massive, radiatively driven winds expected as atomic emission/absorption lines in the ULX spectra. The first evidence for winds was found as residuals in the soft X-ray spectra of ULXs. Very recently, we have been able to resolve these residuals into rest-frame emission and blueshifted (~0.2c) absorption lines arising from highly ionized gas in the deep, high-resolution XMM-Newton spectra of two ULXs. The compact object is therefore surrounded by powerful ultrafast winds as predicted by models of hyper-Eddington accretion. Here we discuss the relevance of these discoveries and the importance of further deep XMM-Newton observations of powerful winds in many other ULXs to estimate the energetics of the wind, the geometry of the system, and the masses of the central accretors.
- Subjects
X-ray binaries; BINARY black holes; XMM-Newton Observatory (Artificial satellite); IONIZED gases; SOFT X rays
- Publication
Astronomische Nachrichten, 2017, Vol 338, Issue 2/3, p234
- ISSN
0004-6337
- Publication type
Article
- DOI
10.1002/asna.201713336