Galactic Centre star formation: the case of the missing gas disc

TL;DR

The paper investigates why a residual gas disc predicted to form with young stars near the Galactic Centre is missing, proposing it was accreted by the black hole, linking star formation to black hole feeding.

Contribution

It demonstrates that residual gas discs are not efficiently removed by known processes, suggesting they are accreted by the black hole, explaining the missing gas at the Galactic Centre.

Findings

Residual gas discs persist for over 10 million years after star formation.

Such gas discs are not observed at present, implying they have been accreted by the black hole.

The accreted gas may power Sgr A*, connecting star formation and black hole activity.

Abstract

We study the dynamical evolution of stars and gas close to the centre of the Milky Way. Any plausible means of forming the young stars observed at the Galactic Centre leaves behind a residual gas disc at ~0.01pc radii. We show that the combined effects of viscous accretion and gravitational interactions with stars do not remove the residual gas efficiently, and that a substantial gas disc, interior to the stellar disc, persists for >10Myr after the stars form. Since no such disc is currently seen at the Galactic Centre we argue that it has been accreted by the super-massive black hole. This scenario offers an attractive connection between nuclear star formation and black hole feeding, and we suggest that the "missing" gas may have been used to power Sgr A*.