2021MNRAS.506.2170S

The interaction of Galactic centre (GC) super bubbles (GSBs) with the gaseous disc and halo of the Milky Way is investigated using radio continuum, X-ray, H I, and CO line surveys. The radio North Polar Spur (NPS) constitutes the brightest eastern ridge of GSB, brightening towards the galactic plane and reaching l = 22^*, b = +2^* at the sharpest end, where it intersects the tangential direction of the 3-kpc-expanding ring and crater. Examination of the spur ridges reveals that the entire GSB, including the NPS and its counter spurs, constitutes a GC-symmetrical Ω/ Y shape. The thickness and gas density of the H I and CO discs are shown to increase sharply from the inside (lower longitude) to the outside the 3-kpc crater. Formation of crater is explained by the sweeping of the upper layer of disc gas by the shock wave from the GC by the explosion ∼10My ago with the emitted energy of several 10⁵⁵erg. Based on the discussion, a unified view on the structure and formation mechanism of GSB is presented.