Misaligned Jets from Sgr A* and the Origin of Fermi/eROSITA Bubbles
Kartick C. Sarkar, Santanu Mondal, Prateek Sharma, Tsvi Piran
Abstract
Abstract 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 × 10 44 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 (≈10 40.5−41 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.