Soft and Supersoft X-ray Sources in Symbiotic Stars

TL;DR

This study uses population synthesis to estimate the occurrence rates and distributions of soft and supersoft X-ray sources in symbiotic stars, aligning well with observed data.

Contribution

It provides the first comprehensive population synthesis analysis of soft and supersoft X-ray sources in symbiotic stars, estimating their occurrence rates and distributions.

Findings

Galactic soft X-ray sources occur at 2-20 per year.

Galactic supersoft X-ray sources occur at 2-17 per year.

Number of X-ray sources in symbiotic stars ranges from 2390 to 6120.

Abstract

Assuming that soft X-ray sources in symbiotic stars result from strong thermonuclear runaways, and supersoft X-ray sources from weak thermonuclear runaways or steady hydrogen burning symbiotic stars, we investigate the Galactic soft and supersoft X-ray sources in symbiotic stars by means of population synthesis. The Galactic occurrence rates of soft X-ray sources and supersoft X-ray sources are from $\sim$ 2 to 20 $\rm yr^{-1}$, and $\sim$ 2 to 17 $\rm yr^{-1}$, respectively. The numbers of X-ray sources in symbiotic stars range from 2390 to 6120. We simulate the distribution of X-ray sources over orbital periods, masses and mass-accretion rates of white dwarfs. The agreement with observations is reasonable.