Tidal disruption events as the origin of the <i>eROSITA</i> and <i>Fermi</i> bubbles

Context . The recently discovered spherical eROSITA bubbles extend up to a latitude of ±80°−85° in the X-ray regime of the Milky Way halo. Similar to the γ -ray Fermi bubbles, they evolve around the Galactic center, making a common origin plausible. However, the driving mechanism and evolution of both bubbles are still under debate. Aims . We investigate whether hydrodynamic energy injections at the Galactic center, such as tidal disruption events, could have inflated both bubbles. The supermassive black hole Sagittarius A* is expected to tidally disrupt a star every 10–100 kyr, potentially leading to an outflow from the central region that drives a shock propagating into the Galactic halo due to its vertically declining density distribution, ultimately forming a superbubble that extends out of the disk similar to the eROSITA and Fermi bubbles. Methods . We model tidal disruption events in the Galaxy using three-dimensional hydrodynamical simulations, considering different Milky Way mass models and tidal disruption event rates. We then generate synthetic X-ray maps and compare them with observations. Results . Our simulation results of a β-model Milky Way halo show that superbubbles, blown for 16 Myr by regular energy injections at the Galactic center that occur every 100 kyr, can have a shape, shell stability, size, and evolution time similar to estimates for the eROSITA bubbles, and an overall structure reminiscent of the Fermi bubbles. The γ -rays in our model would stem from cosmic ray interactions at the contact discontinuity, where they were previously accelerated by first-order Fermi acceleration at in situ shocks. Conclusions . Regular tidal disruption events in the past 10–20 million years near the Galactic center could have driven an outflow resulting in both, the X-ray emission of the eROSITA bubbles and the γ -ray emission of the Fermi bubbles.