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Evidence for Optically Thick, Eddington-limited Winds Driven by Supercritical Accretion

Zhou, Yu and Feng, Hua and Ho, Luis C. and Yao, Yuhan (2019) Evidence for Optically Thick, Eddington-limited Winds Driven by Supercritical Accretion. Astrophysical Journal, 871 (1). Art. No. 115. ISSN 1538-4357. http://resolver.caltech.edu/CaltechAUTHORS:20190125-160631429

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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/aaf724DOIArticle
https://arxiv.org/abs/1812.02923arXivDiscussion Paper
ORCID:
AuthorORCID
Feng, Hua0000-0001-7584-6236
Ho, Luis C.0000-0001-6947-5846
Yao, Yuhan0000-0001-6747-8509
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.
Funders:
Funding AgencyGrant Number
National Program on Key Research and Development Project2018YFA0404502
National Program on Key Research and Development Project2016YFA040080X
National Natural Science Foundation of China11633003
National Natural Science Foundation of China11821303
National Program on Key Research and Development Project2016YFA0400702
National Natural Science Foundation of China11473002
National Natural Science Foundation of China11721303
Subject Keywords:accretion, accretion disks – black hole physics – X-rays: binaries – X-rays: stars
Record Number:CaltechAUTHORS:20190125-160631429
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190125-160631429
Official Citation:Yu Zhou et al 2019 ApJ 871 115
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92484
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:29 Jan 2019 19:30
Last Modified:29 Jan 2019 19:30

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