Fe xxv line profiles in colliding wind binaries

TL;DR

This paper models the Fe XXV line profiles in colliding wind binaries to understand how their shapes vary with orbital phase, aiding the interpretation of future high-resolution X-ray observations.

Contribution

It introduces synthetic line profiles based on a simple wind-wind interaction model to probe stellar wind properties in massive binaries.

Findings

Profiles vary with orbital phase and orientation.

Synthetic profiles can constrain wind properties.

Preparation for high-resolution X-ray data analysis.

Abstract

Strong wind-wind collisions in massive binaries generate a very hot plasma that frequently produces a moderately strong iron line. The morphology of this line depends upon the properties of the wind interaction zone and its orientation with respect to the line of sight. As the binary components revolve around their common centre of mass, the line profiles are thus expected to vary. With the advent of the next generation of X-ray observatories (Astro-H, Athena) that will offer high-resolution spectroscopy above 6 keV, it will become possible to exploit these changes as the most sensitive probe of the inner parts of the colliding wind interaction. Using a simple prescription of the wind-wind interaction in an early-type binary, we have generated synthetic line profiles for a number of configurations and orbital phases. These profiles can help constrain the properties of the stellar winds in such binary systems.