Symbiotic star candidates in inner Galactic disk

Although the GRXE continuum is largely resolved into discrete populations of cataclysmic variables and coronally active stars, these sources exhibit Fe XXV equivalent widths significantly lower than that of the total GRXE, leaving the intense iron line emission unexplained.

In this work, we cross-correlated the XMM-Newton survey of the inner Galactic disk with Gaia DR3 astrometry to identify and characterize hard X-ray sources (>2keV) with reliable stellar counterparts. We selected 107 X-ray sources located within the red giant branch of the color-magnitude diagram, many of which are verified long-period variables. These sources exhibit high X-ray luminosities (Lx~10^31^-10^33^erg/s), significantly exceeding the typical coronal saturation levels of single giants.