X-ray Modeling of \eta\ Carinae and WR140 from SPH Simulations

TL;DR

This paper models X-ray emissions from colliding wind binaries taarinae and WR140 using 3D SPH simulations, successfully reproducing observed light curves and exploring effects of wind properties and cooling.

Contribution

It introduces advanced 3D SPH models that incorporate absorption, extended emission, and radiative effects to interpret X-ray observations of colliding wind binaries.

Findings

Models closely match RXTE X-ray light curves for WR140.

Point-source approximation explains taar's early X-ray recovery.

Discrepancy in taar's extended minimum due to hot bubble formation.

Abstract

The colliding wind binary (CWB) systems \eta\ Carinae and WR140 provide unique laboratories for X-ray astrophysics. Their wind-wind collisions produce hard X-rays that have been monitored extensively by several X-ray telescopes, including RXTE. To interpret these RXTE X-ray light curves, we model the wind-wind collision using 3D smoothed particle hydrodynamics (SPH) simulations. Adiabatic simulations that account for the absorption of X-rays from an assumed point source at the apex of the wind-collision shock cone by the distorted winds can closely match the observed 2-10keV RXTE light curves of both \eta\ Car and WR140. This point-source model can also explain the early recovery of \eta\ Car's X-ray light curve from the 2009.0 minimum by a factor of 2-4 reduction in the mass loss rate of \eta\ Car. Our more recent models relax the point-source approximation and account for the spatially extended emission along the wind-wind interaction shock front. For WR140, the computed X-ray light curve again matches the RXTE observations quite well. But for \eta\ Car, a hot, post-periastron bubble leads to an emission level that does not match the extended X-ray minimum observed by RXTE. Initial results from incorporating radiative cooling and radiatively-driven wind acceleration via a new anti-gravity approach into the SPH code are also discussed.