Energy-dependent evolution in IC10 X-1: hard evidence for an extended corona, and implications

Abstract

We have analyzed a ~130 ks XMM-Newton observation of the dynamically confirmed black hole + Wolf-Rayet (BH+WR) X-ray binary (XB) IC10 X-1, covering ~1 orbital cycle. This system experiences periodic intensity dips every ~35 hours. We find that energy-independent evolution is rejected at a >5 sigma level. The spectral and timing evolution of IC10 X-1 are best explained by a compact disk blackbody and an extended Comptonized component, where the thermal component is completely absorbed and the Comptonized component is partially covered during the dip. We consider three possibilities for the absorber: cold material in the outer accretion disk, as is well documented for Galactic neutron star (NS) XBs at high inclination; a stream of stellar wind that is enhanced by traveling through the L1 point; and a spherical wind. We estimated the corona radius (r_ADC) for IC10 X-1 from the dip ingress to be ~1 E+6 km, assuming absorption from the outer disk, and found it to be consistent with the relation between r_m ADC and 1--30 keV luminosity observed in Galactic NS XBs that spans 2 orders of magnitude. For the other two scenarios, the corona would be larger. Prior BH mass (M_BH) estimates range over 23--38 M_Sun, depending on the inclination and WR mass. For disk absorption, the inclination, i, is likely to be ~60--80 degrees, with M_BH ~24--41 M_Sun. Alternatively, the L1-enhanced wind requires i ~80 degrees, suggesting ~24--33 M_Sun. For a spherical absorber, i ~ 40 degrees, and M_BH ~50--65 M_Sun.

Accepted for publication in ApJ; 10 pages, 4 figures

References in corpus (11)

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• The accretion environment in Vela X-1 during a flaring period using XMM-Newton
• NGC300 X-1 and IC10 X-1: a new breed of black hole binary?
• A Seyfert-2-like Spectrum in the High-Mass X-ray Binary Microquasar V4641 Sgr

Cited by in corpus (6)

• Revisiting the Dynamical Case for a Massive Black Hole in IC10 X-1
• The non-thermal superbubble in IC 10: the generation of cosmic ray electrons caught in the act
• CG X-1: an eclipsing Wolf-Rayet ULX in the Circinus galaxy
• On the Spin of the Black Hole in IC 10 X-1
• Probing the Stellar Wind of the Wolf-Rayet Star in IC 10 X-1
• XMM-Newton and Chandra observations of the M31 globular cluster black hole candidate XB135: a heavyweight contender cut down to size