Black Hole and Neutron Star Transients in Quiescence
Abstract
We consider the X-ray luminosity difference between neutron star and black hole soft X-ray transients (NS and BH SXTs) in quiescence. The current observational data suggest that BH SXTs are significantly fainter than NS SXTs. The luminosities of quiescent BH SXTs are consistent with the predictions of binary-evolution models for the mass transfer rate if (1) accretion occurs via an advection-dominated accretion flow (ADAF) in these systems and (2) the accreting compact objects have event horizons. The luminosities of quiescent NS SXTs are not consistent with the predictions of ADAF models when combined with binary-evolution models, unless most of the mass accreted in the ADAF is prevented from reaching the neutron star surface. We consider the possibility that mass accretion is reduced in quiescent NS SXTs because of an efficient propeller and develop a model of the propeller effect that accounts for the observed luminosities. We argue that modest winds from ADAFs are consistent with the observations, while strong winds are probably not.
Additional Information
© 1999. The American Astronomical Society. Received 1998 October 16; accepted 1999 February 24. We are grateful to Josh Grindlay, Mario Livio, Philip Podsiadlowski, Dimitrios Psaltis, and Eliot Quataert for useful discussions, and to an anonymous referee for constructive comments. A. E. and R. N. also gratefully acknowledge their conversation with Shuang-Nan Zhang, who suggested the idea of a propeller effect in the context of a quasi-spherical accretion flow. This work was supported in part by NASA grant NAG 5-2837. K. M. was supported by a Smithsonian Astrophysical Observatory (SAO) Predoctoral Fellowship and a French Higher Education Ministry Grant. A. E. was supported by a National Science Foundation Graduate Research Fellowship and by NASA through AXAF Fellowship grant PF8-10002 awarded by the AXAF Science Center, which is operated by the SAO for NASA under contract NAS8-39073.Attached Files
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Additional details
- Eprint ID
- 75939
- Resolver ID
- CaltechAUTHORS:20170408-142517670
- NAG 5-2837
- NASA
- Smithsonian Astrophysical Observatory
- Ministère de l'Enseignement supérieur
- NSF Graduate Research Fellowship
- PF8-10002
- NASA Chandra Fellowship
- NAS8-39073
- NASA
- Created
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2017-04-21Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field