Location of the bow shock ahead of cloud G2 at the Galactic Center

TL;DR

This study uses magnetohydrodynamic simulations to analyze how the gas cloud G2 interacts with the accretion flow near the Galactic Center black hole, revealing the formation and location of a bow shock.

Contribution

It provides the first detailed MHD simulation of G2's interaction with the accretion flow, identifying the shock structure and timing of the cloud's pericenter crossing.

Findings

The bow shock forms ahead of G2 during its orbit.

The cloud's front crosses pericenter 7-9 months before the center of mass.

Simulations match observed orbital parameters.

Abstract

We perform detailed magnetohydrodynamic simulations of the gas cloud G2 interacting with the accretion flow around the Galactic Center black hole Sgr A*. We take as our initial conditions a steady-state, converged solution of the accretion flow obtained earlier using the general-relativistic magnetohydrodynamic code HARM. Using the observed parameters for the cloud's orbit, we compute the interaction of the cloud with the ambient gas and identify the shock structure that forms ahead of the cloud. We show that for many configurations, the cloud front crosses orbit pericenter 7 to 9 months earlier than the center-of-mass.