V444 Cygni X-Ray and Polarimetric Variability: Radiative and Coriolis Forces Shape the Wind Collision Region
We present results from a study of the eclipsing, colliding-wind binary V444 Cyg that uses a combination of X-ray and optical spectropolarimetric methods to describe the 3D nature of the shock and wind structure within the system. We have created the most complete X-ray light curve of V444 Cyg to date using 40 ks of new data from Swift, and 200 ks of new and archived XMM-Newton observations. In addition, we have characterized the intrinsic, polarimetric phase-dependent behavior of the strongest optical emission lines using data obtained with the University of Wisconsin's Half-Wave Spectropolarimeter. We have detected evidence of the Coriolis distortion of the wind-wind collision in the X-ray regime, which manifests itself through asymmetric behavior around the eclipses in the system's X-ray light curves. The large opening angle of the X-ray emitting region, as well as its location (i.e. the WN wind does not collide with the O star, but rather its wind) are evidence of radiative braking/inhibition occurring within the system. Additionally, the polarimetric results show evidence of the cavity the wind-wind collision region carves out of the Wolf-Rayet star's wind.
Lomax, J. R.; Nazé, Y.; Hoffman, J. L.; Russell, C. M.P.; De Becker, M.; Corcoran, M. F.; Davidson, J. W.; Neilson, H. R.; Owocki, S.; Pittard, J. M.; and Pollock, A. M.T.. 2015. V444 Cygni X-Ray and Polarimetric Variability: Radiative and Coriolis Forces Shape the Wind Collision Region. Astronomy and Astrophysics. Vol.573 https://doi.org/10.1051/0004-6361/201424468 ISSN: 0004-6361