Hydrodynamical simulations of a compact source scenario for the Galactic Center cloud G2

TL;DR

This paper uses hydrodynamical simulations to explore the possibility that the G2 cloud in the Galactic Center is caused by a stellar wind from an embedded star, showing how interactions with the environment shape the cloud's properties.

Contribution

It presents the first detailed hydrodynamical models of a stellar wind scenario for G2, incorporating gravitational, thermal, and ram pressure effects to match observations.

Findings

Most Brγ luminosity originates from dense, filamentary wind regions.

Simulated wind parameters align with those of a young T Tauri star.

Tidal forces significantly shape the wind near pericenter.

Abstract

The origin of the dense gas cloud G2 discovered in the Galactic Center (Gillessen et al. 2012) is still a debated puzzle. G2 might be a diffuse cloud or the result of an outflow from an invisible star embedded in it. We present hydrodynamical simulations of the evolution of different spherically symmetric winds of a stellar object embedded in G2. We find that the interaction with the ambient medium and with the extreme gravitational field of the supermassive black hole in the Galactic Center must be taken into account for such a source scenario. The thermal pressure of the hot and dense atmosphere confines the wind, while its ram pressure shapes it via stripping along the orbit, with the details depending on the wind parameters. Tidal forces squeeze the wind near pericenter, reducing it to a thin and elongated filament. We also find that in this scenario most of the Br\gamma\ luminosity is expected to come from the densest part of the wind, which has a highly filamentary structure with low filling factor. The observations can be best matched by a mass outflow rate of Mdot,w=8.8 x 10^{-8} Msun/yr and a wind velocity of vw = 50 km/s. These values are compatible with those of a young T Tauri star wind, as already suggested by (Scoville & Burkert 2013).