The G2+G2t complex as a fast and massive outflow?

TL;DR

This paper proposes a simulation model where a central outflow interacting with hot gas near SgrA* explains the observed features of the G2 and G2t clouds, suggesting they are byproducts of such outflows.

Contribution

It introduces a new simulation approach showing G2 and G2t as outcomes of a central outflow interacting with surrounding hot gas in the Galactic Center.

Findings

Simulation reproduces G2 and G2t position-velocity features

G2 is modeled as a bow-shock in the outflow head

G2t results from stripping and accumulation of shocked material

Abstract

Observations of the gas component of the cloud G2 in the Galactic Center have revealed its connection to a tail (G2t) lying on the same orbit. More recent studies indicate a connection between G2 and G1, another cloud detected on the blueshifted side of G2's orbit, suggesting a scenario in which G2 is a denser clump in a stream of gas. In this Letter we show that a simulation of an outflow by a central source (possibly a T Tauri star) moving on G2's orbit and interacting with a hot atmosphere surrounding SgrA* can have G2 and G2t as a byproduct. G2 would be the bow-shock formed in the head of the source, while G2t might be the result of the stripping of the rest of the shocked material by the ram pressure of the surrounding hot gas and of its successive accumulation in the trailing region. Mock position-velocity diagrams for the Br$\gamma$ emission for this simulation can indeed reproduce the correct position and velocity of G2t, as well as the more tenuous material in between. Though some tension between the observations and the simulated model remains, we argue that this might be due to issues in the construction of observed position-velocity (PV) diagrams and/or to a poor treatment of some physical processes - like hydrodynamic mixing - in our simulation.