The Masses of Black Holes with Wolf-Rayet Companions
Abstract
Black Holes with Wolf-Rayet companions represent a channel for forming the most massive stellar BHs. The recent, stunning LIGO detection of the gravitational wave signature from a merging stellar BH binary points to the importance of understanding the progenitor systems formation and evolution. The BH+WR binary IC 10 X-1 holds important clues to the puzzle, by helping establish the upper observed BH mass and pointing to an association between maximum possible BH mass and low metallicity environments. However, securing dynamical mass determiniations for WR+BH binaries appears to be complicated by interaction between the radiation field of the BH and the stellar wind. This causes a substantial change to our understanding of IC 10 X-1, and by extension to the mass distribution of BH binaries. A high precision ephemeris derived from a decade of Chandra/XMM X-ray timing observations, when combined with the optical RV curve, reveals a surprizing simultenaity of mid X-ray eclipse and the maximum blueshift velocity of He II emission lines. The optical emission lines appear to originate in a shielded sector of the WR star's stellar wind which escapes total X-ray ionization by the compact object. Unravelling this projection effect is necessary to obtain the system's true mass function. Complementary Chandra, XMM and NuStar datasets offer new insights into the mass and spin of the BH, and the structure of the photo-ionized wind. We will discuss possible routes toward the mass function in BH+WR binaries via multi-wavelength observations, and the additional leverage provided by further constraining the orbital period derivative.
- Publication:
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AAS/High Energy Astrophysics Division #15
- Pub Date:
- April 2016
- Bibcode:
- 2016HEAD...1512031L