3D Hydrodynamic & Radiative Transfer Models of X-ray Emission from Colliding Wind Binaries

TL;DR

This paper develops 3D hydrodynamic and radiative transfer models to simulate X-ray emissions from colliding wind binaries, successfully matching observations for some systems and phases, advancing understanding of stellar wind interactions.

Contribution

It introduces a combined 3D SPH and radiative transfer modeling approach to accurately simulate X-ray emissions from colliding wind binaries, including complex orbital phases.

Findings

Models reproduce Suzaku observations away from periastron.

The model matches η Carinae's spectrum at periastron.

The WR 140 model overestimates flux during periastron.

Abstract

Colliding wind binaries (CWBs) are unique laboratories for X-ray astrophysics. The massive stars in these systems possess powerful stellar winds with speeds up to $\sim$3000 km s$^{-1}$, and their collision leads to hot plasma (up to $\sim10^8$K) that emit thermal X-rays (up to $\sim$10 keV). Many X-ray telescopes have observed CWBs, including Suzaku, and our work aims to model these X-ray observations. We use 3D smoothed particle hydrodynamics (SPH) to model the wind-wind interaction, and then perform 3D radiative transfer to compute the emergent X-ray flux, which is folded through X-ray telescopes' response functions to compare directly with observations. In these proceedings, we present our models of Suzaku observations of the multi-year-period, highly eccentric systems $\eta$ Carinae and WR 140. The models reproduce the observations well away from periastron passage, but only $\eta$ Carinae's X-ray spectrum is reproduced at periastron; the WR 140 model produces too much flux during this more complicated phase.