Sgr A${}^{\ast }$ envelope explosion and the young stars in the centre of the Milky Way

Abstract

Sgr A${}^{\ast }$ is the super massive black hole residing in the centre of the Milky Way. There is plenty of observational evidence that a massive gas cloud fell into the central parsec of the Milky Way $\sim 6$ million years ago, triggering formation of a disc of young stars and activating Sgr A${}^{\ast }$. In addition to the disc, there is an unexplained population of young stars on randomly oriented orbits. Here we hypothesize that these young stars were formed by fragmentation of a massive quasi-spherical gas shell driven out from Sgr A${}^{\ast }$ potential well by an energetic outflow. To account for the properties of the observed stars, the shell must be more massive than $10^5$ Solar masses, be launched from inside $\sim 0.01$~pc, and the feedback outflow has to be highly super-Eddington albeit for a brief period of time, producing kinetic energy of at least $10^{55}$~erg. The young stars in the central parsec of the Galaxy may be a unique example of stars formed from atomic rather than molecular hydrogen, and forged by extreme pressure of black hole outflows.

Accepted (w. minor revisions) to MNRAS Letters

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Cited by in corpus (8)

• The mass of our Milky Way
• The Hills Mechanism and the Galactic Center S-stars
• The Keplerian three-body encounter I. Insights on the origin of the S-stars and the G-objects in the Galactic center
• Analytical and numerical studies of central galactic outflows powered by tidal disruption events -- a model for the Fermi bubbles?
• Warm absorbers: supermassive black hole feeding, and Compton-thick AGN
• Sources and Radiations of the Fermi Bubbles
• Disks of Stars in the Galactic center triggered by Tidal Disruption Events
• A solution to the paradox of youth in the Galactic centre