Investigating the Role of X-ray Photoevaporation and Absorption in Spatially-resolved Circumstellar Disks with Archival X-ray and ALMA Observations

Young, pre-main sequence stars form planets in chemically and physically diverse circumstellar disks. During the early stages of star and planet formation, high energy emission (UV/X-rays) from the central protostar irradiates the circumstellar disk influencing its chemistry, temperature, and dispersal (lifetime). We present preliminary results from an archival Chandra and XMM-Newton X-ray study characterizing the role X-ray irradiation plays in nearby young stars whose circumstellar disks are spatially resolved with ALMA (Atacama Large Millimeter Array) dust continuum emission. Our sample includes approximately 100 X-ray-bright young star-disk systems from several nearby (< 200 pc) star-forming regions. We present results comparing stellar and disk properties (e.g., spectral type, disk mass, radius, inclination) to X-ray spectral characteristics (e.g., intrinsic L_X, kT, NH) to identify whether intrinsically X-ray bright sources are in advanced stages of X-ray photo-dissociation and to explore the relationship between circumstellar line-of-sight inclination with X-ray line-of-sight absorption (NH). A sub-sample of our X-ray bright disks have been identified with ALMA as carbon monoxide (CO) deficient relative to dust mass. Given the strong dependence of carbon and oxygen abundance on X-ray absorption, we compare NH with CO-depletion to investigate whether X-rays absorption is causally related to CO-depletion. This could provide a novel technique for identifying CO-depleted disks using X-ray observations of young stars with known disk inclinations.