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We study the origin of Na I absorbing gas in ultraluminous infrared galaxies motivated by the recent observations by Martin of extremely superthermal linewidths in this cool gas. We model the effects of repeated supernova explosions driving supershells in the central regions of molecular disks with M_d=10^10 M_sun, using cylindrically symmetric gas dynamical simulations run with ZEUS-3D. The shocked swept-up shells quickly cool and fragment by Rayleigh-Taylor instability as they accelerate out of the dense, stratified disks. The numerical resolution of the cooling and compression at the shock fronts determines the peak shell density, and so the speed of Rayleigh-Taylor fragmentation. We identify cooled shells and shell fragments as Na I absorbing gas and study its kinematics. We find that simulations with a numerical resolution of le 0.2 pc produce multiple Rayleigh-Taylor fragmented shells in a given line of sight. We suggest that the observed wide Na I absorption lines, <v> = 320 pm 120 km s^-1 are produced by these multiple fragmented shells traveling at different velocities. We also suggest that some shell fragments can be accelerated above the observed average terminal velocity of 750 km s^-1 by the same energy-driven wind with an instantaneous starburst of sim 10^9 M_sun. The bulk of mass is traveling with the observed average shell velocity 330 pm 100 km s^-1. Our results show that an energy-driven bubble causing Rayleigh-Taylor instabilities can explain the kinematics of cool gas seen in the Na I observations without invoking additional physics relying primarily on momentum conservation, such as entrainment of gas by Kelvin-Helmholtz instabilities, ram pressure driving of cold clouds by a hot wind, or radiation pressure acting on dust. (abridged)
We present an investigation of the metal enrichment of the intra-cluster medium (ICM) by galactic winds and merger-driven starbursts. We use combined N-body/hydrodynamic simulations with a semi-numerical galaxy formation model. The mass loss by galac
Observations of dwarf galaxies suggest the presence of large-scale magnetic fields. However the size and slow rotation of these galaxies appear insufficient to support a mean-field dynamo action to excite such fields. Here we suggest a new mechanism
In this study, we analyze giant Galactic spurs seen in both radio and X-ray all-sky maps to reveal their origins. We discuss two types of giant spurs: one is the brightest diffuse emission near the maps center, which is likely to be related to Fermi
Galaxy clusters are the most massive collapsed structures in the universe whose potential wells are filled with hot, X-ray emitting intracluster medium. Observations however show that a significant number of clusters (the so-called cool-core clusters
We study the z=0 gas kinematics, morphology, and angular momentum content of isolated galaxies in a suite of cosmological zoom-in simulations from the FIRE project spanning $M_{star}=10^{6-11}M_{odot}$. Gas becomes increasingly rotationally supported