Cyg X-3: a low-mass black hole or a neutron star.
Abstract
Cyg X-3 is a highly interesting accreting X-ray binary, emitting from the radio to high-energy gamma-rays. It consists of a compact object wind-fed by a Wolf-Rayet (WR) star, but the masses of the components and the mass-loss rate have been a subject of controversies. Here, we determine its masses, inclination and the mass-loss rate using our derived relationship between the mass-loss rate and the mass for WR stars of the WN type, published infrared and X-ray data, and a relation between the mass-loss rate and the binary period derivative (observed to be >0 in Cyg X-3). Our obtained mass-loss rate is almost identical to that from two independent estimates and consistent with other ones, which strongly supports the validity of this solution. The found WR and compact-object masses are 10.3+ 3.9- 2.8 and 2.4+ 2.1- 1.1 M⊙, respectively. Thus, our solution still allows for the presence of either a neutron star or a black hole, but the latter only with a low mass. However, the radio, infrared and X-ray properties of the system suggest that the compact object is a black hole. Such a low-mass black hole could be formed via accretion-induced collapse or directly from a supernova.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2013
- DOI:
- 10.1093/mnrasl/sls035
- arXiv:
- arXiv:1208.5455
- Bibcode:
- 2013MNRAS.429L.104Z
- Keywords:
-
- binaries: close;
- stars: individual: Cyg X-3;
- stars: winds;
- outflows;
- stars: Wolf-Rayet;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- MNRAS Letters, in press, 5 pages