| dc.description.abstract | In visible light, our Galaxy looks like a flat disk to us. However, in gamma ray, in addition to a flat disk similar to visible light there are two giant bubble-like structures extending several kpc in the Galactic halo in the direction of the Galactic center. The two structures are called Fermi bubbles and numerous mechanisms have been proposed for their formation. We are particular interested in the scenario of a series of tidal disruption events (TDEs) initiated by repeated stellar captures by the supermassive black hole in the Galactic center. We use numerical simulation to study the formation and evolution of the Fermi bubbles. The ambient gas in the halo is modeled as a layered exponential atmosphere, and the TDE is modeled as an outburst of a large amount of energy confined in a small volume enclosing the center (a.k.a. an explosion at the center). The series of explosions can drive an outflow and create the bubbles. A systematic survey of the formation process is performed. We vary the energy of each explosion, the interval between two explosions. With the same total energy, multiple explosion events give a more turbulent inner structure than a single event. Furthermore, we also examine different configurations of ambient magnetic field. In general, magnetic field hinders the development of the bubbles, especially in the high magnetic pressure region. For multiple explosion events with the same energy of each explosion and the same interval between two explosions, the case with magnetic field is more turbulent than the one without magnetic field. Finally, for illustration, we compute the projected X-ray emission from our simulation, and compare with the ROSAT X-ray map at 1.5 keV. | en_US |