Stellar winds pump the heart of the Milky Way

Abstract

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 $\sim 10^{-3}{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$ 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 ($\sim 10^4\mathrm{K}$) in its vicinity raised questions about how such material could settle in the hostile ($\sim 10^7\mathrm{K}$) 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 $\sim 500\mathrm{yr}$ with material being captured at a rate of $\sim 10^{-6}{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$ at scales of $\sim 10^{-4}\mathrm{pc}$, consistent with the observations and previous models. However, on longer timescales ($\gtrsim 3000\mathrm{yr}$) the material accumulates close to the black hole in the form of a disk. Considering the duration of the Wolf-Rayet phase ($\sim 10^5\mathrm{yr}$), 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.

6 pages and 5 figures. Accepted for publication in ApJL

References in corpus (9)

• Physical Properties of Wolf-Rayet Stars
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• An Update on Monitoring Stellar Orbits in the Galactic Center
• An Unambiguous Detection of Faraday Rotation in Sagittarius A*
• Stellar and wind properties of massive stars in the central parsec of the Galaxy
• Variable accretion and emission from the stellar winds in the Galactic centre
• Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center
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• The role of feedback in accretion on Low Luminosity AGN: Sgr A* case study

Cited by in corpus (11)

• Ab Initio Horizon-Scale Simulations of Magnetically Arrested Accretion in Sagittarius A* Fed by Stellar Winds
• The Surprisingly Small Impact of Magnetic Fields On The Inner Accretion Flow of Sagittarius A* Fueled By Stellar Winds
• Magnetically Modified Spherical Accretion in GRMHD: Reconnection-Driven Convection and Jet Propagation
• Evidence for a jet and outflow from Sgr A*: a continuum and spectral line study
• Accretion of a Vlasov gas on to a black hole from a sphere of finite radius and the role of angular momentum
• Colliding Winds in and around the Stellar Group IRS 13E at the Galactic Center
• Near- and mid-infrared observations in the inner tenth of a parsec of the Galactic center -- Detection of proper motion of a filament very close to Sgr~A*
• Flares and their echoes can help distinguish photon rings from black holes with space-Earth very long baseline interferometry
• Upper Limit on Brackett-gamma Emission from the Immediate Accretion Flow onto the Galactic Black Hole
• Galactic center gamma-ray production by cosmic rays from stellar winds and Sgr A East
• Supernovae in colliding-wind binaries: observational signatures in the first year