Evidence for Optically Thick, Eddington-limited Winds Driven by Supercritical Accretion
- Creators
- Zhou, Yu
- Feng, Hua
- Ho, Luis C.
- Yao, Yuhan
Abstract
Supercritical accretion onto compact objects powers a massive wind that is optically thick and Eddington-limited. If most of the hard X-rays from the central disk are obscured by the wind, the source will display a blackbody-like spectrum with a luminosity scaled with the mass of the compact object. From the Chandra archive of nearby galaxies, we selected a sample of luminous and very soft sources and excluded contamination from foreground objects and supernova remnants. They are found to be preferentially associated with late-type galaxies. The majority of sources in our sample are either too hot or too luminous to be explained by nuclear burning on the surface of white dwarfs, and are argued to be powered by accretion. The most likely explanation is that they are due to emission from the photosphere of a wind driven by supercritical accretion onto compact objects. Their blackbody luminosity ranges from ~10^(37) to nearly 10^(40) erg s^(−1), indicative of the presence of both neutron stars and stellar-mass black holes. The blackbody luminosity also shows a possible bimodal distribution, albeit at low significance, peaked around the Eddington limit for neutron stars and stellar-mass black holes, respectively. If this can be confirmed, it will be smoking gun evidence that supercritical accretion powers thick winds. Based on a wind model, the inferred mass accretion rate of these objects is around a few hundred times the Eddington rate, suggesting that they may be intermediate between the canonical ultraluminous X-ray sources and SS 433 in terms of the accretion rate.
Additional Information
© 2019 The American Astronomical Society. Received 2018 September 3; revised 2018 November 26; accepted 2018 December 6; published 2019 January 25. We thank the referee for useful comments, and are grateful to David Meier and Weimin Gu for insightful discussions and comments. H.F. acknowledges funding support from the National Key R&D Project (grants Nos. 2018YFA0404502 and 2016YFA040080X), and the National Natural Science Foundation of China under the grant Nos. 11633003 and 11821303. L.C.H. was supported by the National Key R&D Program of China (grant No. 2016YFA0400702) and the National Science Foundation of China under grant Nos. 11473002 and 11721303.Attached Files
Published - Zhou_2019_ApJ_871_115.pdf
Accepted Version - 1812.02923.pdf
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Additional details
- Eprint ID
- 92484
- Resolver ID
- CaltechAUTHORS:20190125-160631429
- 2018YFA0404502
- National Program on Key Research and Development Project
- 2016YFA040080X
- National Program on Key Research and Development Project
- 11633003
- National Natural Science Foundation of China
- 11821303
- National Natural Science Foundation of China
- 2016YFA0400702
- National Program on Key Research and Development Project
- 11473002
- National Natural Science Foundation of China
- 11721303
- National Natural Science Foundation of China
- Created
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2019-01-29Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field