Simulating the pericentre passage of the Galactic centre star S2

Understand

The so-called S2 star reached its closest approach to the massive black hole (BH) at around 1500 $R_\mathrm{s}$ in May 2018.

• It has been proposed that the interaction of its stellar wind with the high-density accretion flow at this distance from Sgr A* will lead to a detectable, month-long X-ray flare.
• Our goal is to verify whether or not the S2 star wind can be used as a diagnostic tool to infer the properties of the accretion flow towards Sgr A* at its pericentre (an unprobed distance regime), putting important constraints on BH accretion flow models.
• We run a series of three-dimensional adaptive mesh refinement simulations with the help of the Ramses code which include the realistic treatment of the interaction of S2's stellar wind with the accretion flow along its orbit and - apart from hydrodynamical and thermodynamical effects - include the tidal interaction with the massive BH.