Interaction of Galactic Winds and Ambient Medium: A numerical study at 2 scales

The existence of hot, x-ray and gamma-ray emitting bubbles above and below the Galactic plane and the discovery of smaller chimneys traced by radio emission have been interpreted as vestiges of jet-driven nuclear outflows from the Galactic center. I will explore two aspects of the interaction of a nuclear outflow with the gas of its host galaxy with the help of magnetohydrodynamical simulations. First, I will study the effect of jet orientation on the morphology of the resulting x-ray bubbles. Preliminary models indicate a strong dependence of morphology on jet orientation. The resulting simulation data sets will be compared to archival and new observations of the vestigial Galactic center jet. Second, I will investigate cloud entrainment in galactic outflows. Embedded in the hot gas are cold, dense cloudlets, with line-of-sight velocities of several hundred km/s, suggesting that they have been entrained in the hot outflow. Their morphologies resemble that of abraded cloudlets in numerical simulations of galactic outflows. Radio data suggest that at least two of the cloudlets contain molecular gas, which, given the extreme environment, is puzzling. To explore conditions for clouds and molecular gas survival in hot nuclear outflow, I will combine observations and numerical simulations. Numerical simulations containing detailed thermal, magnetic, and cosmic ray physics will be developed to explore scenario of cloud entrainment in hot outflow. The results from the simulation will be compared to near-IR spectra across the leading edges, where outflow and cloudlets presumably interact the most.