Fermi and eRosita bubbles as relics of the past activity of the Galactic
  black hole
  The newly launched X-ray satellite, eRosita, has recently revealed two
gigantic bubbles extending to ~80 degrees above and below the Galactic center.
The morphology of these "eRosita bubbles" bears a remarkable resemblance to the
Fermi bubbles previously discovered by the Fermi Gamma-ray Space Telescope and
its counterpart, the microwave haze. The physical origin of these striking
structures has been intensely debated; however, because of their symmetry about
the Galactic center, they likely originate from some energetic outbursts from
the Galactic center in the past. Here we propose a theoretical model in which
the eRosita bubbles, Fermi bubbles, and the microwave haze could be
simultaneously explained by a single event of jet activity from the central
supermassive black hole a few million years ago. Using numerical simulations,
we show that this model could successfully reproduce the morphology and
multi-wavelength spectra of the observed bubbles and haze, which allows us to
derive critical constraints on the energetics and timescales of the outburst.
This study serves as an important step forward in our understanding of the past
Galactic center activity of our Milky Way Galaxy, and may bring valuable
insights into the broader picture of supermassive black hole-galaxy
co-evolution in the context of galaxy formation.
