Evolution of the hot circumgalactic medium around the Milky Way
Sten Sipma (University of Groningen)
Tuesday 18/11/2025 @ 14:00, Sala Antonio Sollima (IV piano Battiferro)
Studying the hot (T=10^6 K) gas phase of the circumgalactic medium (CGM) around late-type galaxies is crucial due to its connection to the missing baryon problem and the open question of how gas accretes onto galaxies to sustain star formation. We use a simple semi-analytic model assuming hydrostatic equilibrium, radiative cooling, photoionization from galactic sources (the disc, the central molecular zone and the central black hole), and mechanical heating from a source at the centre of the system, to evolve the hot CGM around the Milky Way. The most basic scenario, a purely cooling gas, shows that the gas beyond a few kpc flows towards the centre of the system at a constant rate. In the inner few kpc, however, the gas cools rapidly due to low cooling times. Adding mechanical heating and photoionization lets us estimate the power required to stop this cooling and compare it with the energy released by an event that could have produced the Fermi? and eROSITA?bubbles. Our results show that such an event is sufficient to halt the inflow, and could form a self-regulating cycle with the hot CGM that keeps it stable for a long time.