The black hole in NGC 1313 X-2
Abstract
The amount of data available for NGC 1313 X-2 make it a cornerstone for the study of ultraluminous X-ray sources (ULXs). We modelled the optical and X-ray data of this ULX with a binary evolution code that takes into account X-ray irradiation. We restricted the candidate binary system to be either a 50-100 M_⊙ black hole (BH) accreting from a 12-15 M_⊙ main sequence star or a 20 M_⊙ BH with a 12-15 M_⊙ giant donor. If the orbital period of the system is ∼6 days, a 20 M_⊙ BH model becomes unlikely and we are left with the only possibility that the compact accretor in NGC 1313 X-2 is a massive BH of 50-100 M_⊙. We briefly discuss these results within the framework of an alternative scenario for the formation of ULXs, in which a portion of them may contain BHs of ⪆30-40 M_⊙ formed from very massive stars in a low metallicity environment.
- Publication:
-
Astronomische Nachrichten
- Pub Date:
- May 2011
- DOI:
- 10.1002/asna.201011513
- arXiv:
- arXiv:1011.2038
- Bibcode:
- 2011AN....332..422Z
- Keywords:
-
- accretion;
- accretion disks;
- black hole physics;
- galaxies: individual (NGC 1313);
- stars: individual (NGC 1313 X-2);
- X-rays: binaries;
- X-rays: galaxies;
- \hbox{X-rays:;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 4 pages, 2 figures. Accepted for publication in the Astronomische Nachrichten (Astronomical Notes), to appear in the proceedings of the conference "Ultra-Luminous X-ray sources and Middle Weight Black Holes" (Madrid, May 24-26, 2010)