X-ray Emission from Ionized Wind-Bubbles around Wolf-Rayet Stars
Abstract
Using a code that employs a self-consistent method for computing the effects of photoionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive Wolf-Rayet (W-R) stars. Our algorithm incorporates a simplified model of the photo-ionization source, computes the fractional ionization of hydrogen due to the photoionizing flux and recombination, and determines self-consistently the energy balance due to ionization, photo-heating and radiative cooling. We take into account changes in stellar properties and mass-loss over the star's evolution. Our multi-dimensional simulations clearly reveal the presence of strong ionization front instabilities. Using various X-ray emission models, and abundances consistent with those derived for W-R nebulae, we compute the X-ray flux and spectra from our wind bubble models. We show the evolution of the X-ray spectral features with time over the evolution of the star, taking the absorption of the X-rays by the ionized bubble into account. Our simulated X-ray spectra compare reasonably well with observed spectra of Wolf-Rayet bubbles. They suggest that X-ray nebulae around massive stars may not be easily detectable, consistent with observations.
Cite
@article{arxiv.1508.04790,
title = {X-ray Emission from Ionized Wind-Bubbles around Wolf-Rayet Stars},
author = {Vikram V. Dwarkadas and Duane Rosenberg},
journal= {arXiv preprint arXiv:1508.04790},
year = {2015}
}
Comments
3 pages, 4 figures. To be published in the Proceedings of the International Workshop on Wolf-Rayet Stars, Potsdam, 1-5 June 2015. Editors W.-R. Hamann, A. Sander, and H. Todt