XMM-Newton study of X-ray sources in the field of Willman 1 dwarf spheroidal galaxy

TL;DR

This study analyzes X-ray sources in the Willman 1 dwarf galaxy using XMM-Newton data, classifying sources and identifying a symbiotic star, foreground star, and background galaxies, revealing low luminosity sources similar to other dwarf galaxies.

Contribution

First comprehensive X-ray source catalog and classification for Willman 1, including identification of a symbiotic star and detailed source properties.

Findings

97 X-ray sources catalogued in Wil 1

Detection of a $eta$-type symbiotic star

X-ray luminosities do not exceed 10^34 erg s^-1

Abstract

We present the results of the analysis of three XMM-Newton observations of the Willman 1 dwarf spheroidal galaxy (Wil 1). X-ray sources are classified on the basis of spectral analysis, hardness ratios, X-ray-to-optical flux ratio, X-ray variability, plus cross-correlation with available catalogues in optical and infrared wavelengths. We catalogued 97 sources in the field of Wil 1. Our classification shows the presence of a $\beta$-type symbiotic star in Wil 1. We classified one M dwarf foreground star in the field of Wil 1. Moreover, fifty-four sources are classified as background AGNs and galaxies. Our study shows that the luminosity of the X-ray sources of Wil 1 does not exceed $\sim$10$^{34}$ erg s$^{-1}$ in the energy range of 0.2--12.0 keV, which is similar to observed luminosities of sources in nearby dwarf spheroidal galaxies.