The coupling of a young stellar disc with the molecular torus in the Galactic centre

TL;DR

This study uses numerical simulations to show that the young stellar disc in the Galactic centre can naturally evolve into the observed perpendicular orientation due to gravitational interactions with the molecular torus and late-type stars.

Contribution

It demonstrates through N-body simulations that the stellar disc's evolution can explain its observed orientation and properties in the Galactic centre.

Findings

The stellar disc naturally reaches a perpendicular orientation to the torus.

The evolution is consistent with the observed configuration within the stars' lifetime.

The early-type stars may have originated from a single gaseous disc.

Abstract

The Galactic centre hosts, according to observations, a number of early-type stars. About one half of those which are orbiting the central supermassive black hole on orbits with projected radii $\gtrsim$ 0.03 pc form a coherently rotating disc. Observations further reveal a massive gaseous torus and a significant population of late-type stars. In this paper, we investigate, by means of numerical N-body computations, the orbital evolution of the stellar disc, which we consider to be initially thin. We include the gravitational influence of both the torus and the late-type stars, as well as the self-gravity of the disc. Our results show that, for a significant set of system parameters, the evolution of the disc leads, within the lifetime of the early-type stars, to a configuration compatible with the observations. In particular, the disc naturally reaches a specific - perpendicular - orientation with respect to the torus, which is indeed the configuration observed in the Galactic centre. We, therefore, suggest that all the early-type stars may have been born within a single gaseous disc.