Abstract Details

Name: Sayantan Bhattacharya
Affiliation: University of Massachusetts, Lowell
Conference ID: ASI2021_73
Title : What's The Mass of IC 10 X-1 ?
Authors and Co-Authors : Sayantan Bhattacharya(University Of Massachusetts, Lowell), Andre-Nicolas Chene(Gemini Observatory North, Hawaii), Ankur Roy(University Of Massachusetts, Lowell), Rigel C. Cappallo (University Of Massachusetts, Lowell), Silas G. T. Laycock(University Of Massachusetts, Lowell), Dimitris M. Christodoulou(University of Massachusetts Lowell)
Abstract Type : Poster
Abstract Category : Extragalactic Astronomy
Abstract : IC 10 X-1 is a high mass X-ray binary (HMXB) that consists of a black hole (BH) and a Wolf-Rayet (WR) star with an orbital period of 34.9 hours. In a series of Chandra and XMM-Newton observations, eclipses were discovered with a duration of ~5 hours. The source shows consistent variability around an X-ray luminosity of 7x10^37 erg s^-1, in which the optical radial-velocity (RV) measurements from the He II line showed a phase shift compared to the X-ray ephemeris of the system. This observation put in question the mass determination of the BH -- either the He II line originates in a shadowed region of the stellar wind (hence it does not trace directly the motion of the WR star), or the BH is eclipsed by a trailing shock or plume. A shock front must be forming where the WR wind collides with wind emanating from the BH and its accretion disk. To understand the influence of X-rays on the WR optical spectrum, we used CMFGEN to model a spectrum with X-rays embedded in the WR wind. CMFGEN takes into account non-LTE atmospheres and solves for the radiation fi eld in comoving coordinates, but it uses a spherical geometry that does not account for asymmetries. We are using archival optical spectra in order to generate RV plots from other lines originating deeper inside the WR photosphere and compare them to those obtained from the current model. We hope that this investigation will lead to a more accurate determination of the BH mass in this HMXB.