2023ApJ...951...36S

One of the leading explanations for the origin of Fermi Bubbles is past jet activity in the Galactic center supermassive black hole Sgr A^*. The claimed jets are often assumed to be perpendicular to the Galactic plane. Motivated by the orientation of pc-scale nuclear stellar disk and gas streams, as well as a low inclination of the accretion disk around Sgr A^* inferred by the Event Horizon Telescope, we perform hydrodynamical simulations of nuclear jets significantly tilted relative to the Galactic rotation axis. The observed axisymmetry and hemisymmetry (north-south symmetry) of Fermi/eROSITA bubbles (FEBs) due to quasi-steady jets in Sgr A^* could be produced if the jet had a super-Eddington power (≳5 × 10⁴⁴ erg s^–1) for a short time (jet active period ≲6 kyr) for a reasonable jet opening angle (≲10°). Such powerful explosions are, however, incompatible with the observed O VIII/O VII line ratio toward the bubbles, even after considering electron-proton temperature nonequilibrium. We argue that the only remaining options for producing FEBs are (i) a low-luminosity (≈10⁴0.5-41 erg s^–1) magnetically dominated jet or accretion wind from the Sgr A^*, or (ii) a supernovae or tidal disruption event driven wind of a similar luminosity from the Galactic center.