Circumgalactic Medium of our Galaxy in X-ray absorption

To test if the z=0 super-virial phase detected toward extragalactic QSO sightlines in absorption are from the ISM of our Milky Way, we look for the tracers of the super-virial phase, i.e., Ne X, Si XIV, and S XVI, toward Galactic X-ray binaries (Lara-DI, Krongold, Mathur, Das, et al. 2024, MNRAS, 533, 287). From the non-detection, we infer that the gas likely comes from the extraplanar region beyond the ISM or the extended CGM.

We report the first detection of nonthermal broadening of O VII lines in the warm-hot ≈1e6 K circumgalactic medium of the Milky Way (Das S., 2024, ApJL, 963, L48).  In addition to the main goal of studying the target quasars, the same data has been used before to study the density and mass distribution of the warm-hot CGM of our Galaxy and external galaxies, warm-hot intergalactic medium, and super-virial 1e7 K hot phase in the CGM of our Galaxy. Our paper opens up a new dimension to utilize the existing data that has not been explored before.

Simultaneous (and first) detection and characterization of super-virial (1e7.5 K), virial (1e6.2 K),  and sub-virial (1e5.5 K) phases of the CGM of the Milky Way probed in X-ray absorption: evidence for non-solar chemical composition and non-thermal line broadening (Das et al. 2021, ApJ, 918, 83). The CGM is multi-phase even in X-ray, and way more complex than is usually assumed!