Constraining the hot phase of the Milky Way with eROSITA

The growth of galaxies in the local Universe critically depends on the interplay between the hot plasma with the other phases of the interstellar medium (ISM). As a prototype for typical spiral galaxies, the Milky Way offers the unique opportunity to capture the important details of such feedback all the way from sub-parsec to galactic scales. In the 90's, the ROSAT all-sky X-ray maps confirmed the existence of a hot component of the ISM, the Galactic corona. However, because of strong obscuration in the soft X-ray energy band, those maps have a limited horizon of ~1 kpc in the Galactic plane. Recent XMM and Chandra surveys of the Galactic centre demonstrate that the hot ISM phase can be traced throughout the disc in the harder X-ray band, confirming the importance of the hot phase of the Milky Way. However, so far only less than 0.03% of the Milky Way has been covered by the narrow fields of view of current X-ray imaging telescopes. The eROSITA all-sky survey will rectify this state of affairs, allowing us to trace the connection and feedback between the Galactic corona and halo with the energetic activity at the GC (e.g., due to cosmic rays, stellar and AGN outflows).