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