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Description
The central super-massive black hole of the Milky Way, Sgr A, accretes at a very low rate making it a very underluminous galactic nucleus. Despite the tens of Wolf-Rayet stars present within the inner parsec supplying $\sim10^{−3}\rm M_{\odot}\ yr^{-1}$ in stellar winds, only a negligible fraction of this material ($<10^{-4}$) ends up being accreted onto Sgr A. The recent discovery of cold gas ($\sim 10^4\rm\ K$) in its vicinity raised questions about how such material could settle in the hostile ($\sim10^7\rm\ K$) environment near Sgr A. In this work we show that the system of mass-losing stars blowing winds can naturally account for both the hot, inefficient accretion flow, as well as the formation of a cold disk-like structure. We run hydrodynamical simulations using the grid-based code RAMSES starting as early in the past as possible to observe the state of the system at the present time. Our results show that the system reaches a quasi-steady state in about $\sim500\rm\ yr$ with material being captured at a rate of $\sim10^{−6}\rm\ M_{\odot}\ yr^{-1}$ at scales of $\sim10^{-4}$ pc , consistent with the observations and previous models. However, on longer timescales ( $>3000$ yr ) the material accumulates close to the black hole in the form of a disk. Considering the duration of the Wolf-Rayet phase ( $\sim10^{5}$ yr ), we conclude that this scenario likely has already happened, and could be responsible for the more active past of Sgr A, and/or its current outflow. We argue that the hypothesis of the mass-losing stars being the main regulator of the activity of the black hole deserves further consideration.