Simulations of the formation of a gaseous disc and young stars near Sgr A* via cloud-cloud collisions

TL;DR

This study uses numerical simulations to explore whether collisions of massive gas clouds near Sgr A* can produce the observed young star populations and gaseous structures, aligning with key observational features.

Contribution

It demonstrates that cloud-cloud collisions can form gaseous discs and stellar distributions consistent with observations near Sgr A*, providing a plausible formation scenario.

Findings

Simulations produce inner gaseous discs and eccentric filaments matching observations.

Radial stellar mass distribution follows a steep R^-2 profile.

Gas accretion rates could power Sgr A* near its Eddington limit.

Abstract

Young massive stars in the central parsec of our Galaxy are best explained by star formation within at least one, and possibly two, massive self-gravitating gaseous discs. With help of numerical simulations, we here consider whether the observed population of young stars could have originated from a large angle collision of two massive gaseous clouds at R ~ 1 pc from Sgr A*. In all the simulations performed, the post-collision gas flow forms an inner nearly circular gaseous disc and one or two eccentric outer filaments, consistent with the observations. Furthermore, the radial stellar mass distribution is always very steep, sigma proportional to R^-2, again consistent with the data. The 3D velocity structure of the stellar distribution is however sensitive to initial conditions (e.g., the impact parameter of the clouds) and gas cooling details. In all the cases the amount of gas accreted by our inner boundary condition is large, enough to allow Sgr A* to radiate near its Eddington limit during ~ 10^5 years. This suggests that a refined model would have physically larger clouds (or a cloud and a disc such as the CND) colliding at a distance of a few pc rather than 1 pc as in our simulations.