Mini-spiral as source of material for Sgr A* in bright state

TL;DR

This paper proposes that the Galactic Center mini-spiral supplies sufficient material to sustain Sgr A*'s bright activity, with collisions reducing angular momentum and enabling accretion episodes.

Contribution

It introduces the mini-spiral as a significant source of accreting material for Sgr A* and discusses the dynamics leading to bright activity phases.

Findings

Mini-spiral contains enough material to power Sgr A*'s luminosity.

Collisions among clumps reduce angular momentum, enabling accretion.

Accretion episodes occur via a transient ring mode at ~10^4 Rg.

Abstract

The question of the origin of the gas supplying the accretion process is pertinent especially in the context of enhanced activity of Galactic Center during the past few hundred years, seen now as echo from the surrounding molecular clouds, and the currently observed new cloud approaching Sgr A*. We discuss the so-called Galactic Center mini-spiral as a possible source of material feeding the supermassive black hole on a 0.1 parsec scale. The collisions between individual clumps reduce their angular momentum. and set some of the clumps on a plunging trajectory. We conclude that the amount of material contained in the mini-spiral is sufficient to sustain the luminosity of Sgr A* at the required level. The accretion episodes of relatively dense gas from the mini-spiral passing through a transient ring mode at $\sim 10^4$ Rg provide a viable scenario for the bright phase of Galactic Center.