Dynamic modeling and virtual-reality exploration of the X-ray emission and accretion flow in the Galactic center from colliding stellar winds

The Galactic center is a prime candidate for studying the Bondi-radius/parsec-size flow of matter towards a supermassive black hole (SMBH) due to our ability to resolve the sources that are continually injecting material into this region. Hydrodynamic simulations of the inner parsec’s dominant injection source — the stellar winds of ~25 Wolf-Rayet stars orbiting the SMBH Sgr A* — reproduce not only the inferred accretion rate down to a radius of 0.1pc, but also the diffuse X-ray emission seen by the Chandra X-ray Observatory in terms of flux level and spectral shape. This indicates that the X-ray emission in the region of comparison (a 2-5 arcsec annulus centered on the SMBH) is from Wolf-Rayet wind collisions. Two sets of more recent simulations, one that includes the 65 OB stellar winds and the other that shows an accretion disk similar to that recently reported in ALMA observations, show the same intriguing difference with the earlier work: the X-ray emission centered on Sgr A* is notably reduced. This is important for rectifying how the modeled colliding-wind emission and the unmodeled X-rays produced much nearer to Sgr A* itself via its radiatively inefficient accretion flow (RIAF) sum together to produce the observed, quiescent X-ray properties in line of sight with Sgr A*. We will present our newer simulations, their synthesized X-ray emission, and additional constraints we can derive on the RIAF through comparisons with Chandra observations. This includes newly incorporated dust scattering, which both spatially spreads out the X-ray emission and modifies the X-ray spectrum, as well as predictions for future missions with improved energy resolution by incorporating the velocity of the X-ray-emitting gas into the X-ray synthesis calculation to compute X-ray line profiles.

The second component of our presentation is “Galactic Center VR”, which is our outreach app for exploring the simulation output in virtual reality. Available for free on the Steam and Viveport VR stores (https://store.steampowered.com/app/1240350/Galactic_Center_VR/), GCVR users can move anywhere they want within the simulation while looking in any direction they choose via VR goggles and controllers, all while undergoing 500 years of simulation evolution. In addition to discussing how we plan to add VR tools that will take this from an outreach tool to a research tool, we will bring our VR setup with us to give demonstrations to interested participants.