How Massive are the Heaviest Black Holes in X-ray Binaries? Exploring IC 10 X-1 and its Kind.
Abstract
Black hole X-ray binaries represent a unique probe of stellar evolution and the most extreme physical conditions found in nature. The X-ray binary IC 10 X-1 occupies an important niche as a link between BH-XRBs and Ultra Luminous X-ray Sources (ULX) due to its intermediate luminosity (10^38 erg/s), and role as a central exemplar of the association of between low metallicity galaxies and maximum BH mass.The most secure and direct dynamical evidence for any BH mass comes from the radial velocity (RV) curve coupled with eclipse timing measurements. We phase-connected X-ray timing data accumulated over a decade with Chandra/XMM, with the optical RV curve, revealing a surprizing simultenaity of mid X-ray eclipse and the maximum blueshift velocity of He II emission lines. Our interpretation is that the optical emission lines originate in a shadowed sector of the WR star's stellar wind which escapes X-ray ionization by the compact object. The RV shifts are therefore a projection effect of the stellar wind, and unrelated to the system's mass function which becomes completely unknown. Chandra, XMM and NuStar datasets present a complex picture of radiative transfer through a photo-ionized wind. A search for the orbital period derivative (P-dot) by X-ray timing offers additonal insights, and we present a simulation for the feasibility of constraining P-dot via optical means.This is a substantial change to our understanding of IC 10 X-1, and with similar results reported for its "near twin" NGC 300 X-1, adds new a dimension to the facinating question of the maximum mass for stellar BHs.
- Publication:
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American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016
- Bibcode:
- 2016AAS...22721807L