Numerical simulations of the possible origin of the two sub-parsec scale and counter-rotating stellar disks around SgrA*

TL;DR

This paper presents high-resolution simulations showing how a collision between a molecular cloud and a circum-nuclear disk can produce the two counter-rotating stellar disks observed around SgrA* in the Milky Way, explaining their origin.

Contribution

It introduces a novel model where a single cloud collision leads to the formation of two inclined, counter-rotating disks, matching observed features at the Galactic Center.

Findings

Simulation reproduces counter-rotating disks formation

Predicts spiral filaments feeding the Galactic Center

Aligns with observed mini-spiral structure

Abstract

We present a high resolution simulation of an idealized model to explain the origin of the two young, counter-rotating, sub-parsec scale stellar disks around the supermassive black hole SgrA* at the Center of the Milky Way. In our model, the collision of a single molecular cloud with a circum-nuclear gas disk (similar to the one observed presently) leads to multiple streams of gas flowing towards the black hole and creating accretion disks with angular momentum depending on the ratio of cloud and circum-nuclear disk material. The infalling gas creates two inclined, counter-rotating sub-parsec scale accretion disks around the supermassive black hole with the first disk forming roughly 1 Myr earlier, allowing it to fragment into stars and get dispersed before the second, counter-rotating disk forms. Fragmentation of the second disk would lead to the two inclined, counter-rotating stellar disks which are observed at the Galactic Center. A similar event might be happening again right now at the Milky Way Galactic Center. Our model predicts that the collision event generates spiral-like filaments of gas, feeding the Galactic Center prior to disk formation with a geometry and inflow pattern that is in agreement with the structure of the so called mini-spiral that has been detected in the Galactic Center.