We have analyzed a \sim 130 ks XMM-Newton observation of the dynamically confirmed black hole + Wolf-Rayet ( BH+WR ) X-ray binary ( XB ) IC10 X-1 , covering \sim 1 orbital cycle .
This system experiences periodic intensity dips every \sim 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 \sim 10 ^ { 6 } km , assuming absorption from the outer disk , and found it to be consistent with the relation between r _ { 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 _ { \odot } , depending on the inclination and WR mass .
For disk absorption , the inclination , i , is likely to be \sim 60–80 ^ { \circ } , with M _ { BH } \sim 24–41 M _ { \odot } .
Alternatively , the L1-enhanced wind requires i \sim 80 ^ { \circ } , suggesting \sim 24–33 M _ { \odot } .
For a spherical absorber , i \sim 40 ^ { \circ } , and M _ { BH } \sim 50–65 M _ { \odot } .