2007/10/31 by Alexei O. Razoumov, Michael L. Norman, J. X. Prochaska +6
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/589136
12 Pages, 9 Figures, accepted to ApJ, printing in colour recommended
arxiv created 2008/04/05 · openalex publication_date 2008/08/07 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/07/28
The median observed velocity width v90 of low-ionization species in damped Ly-alpha systems is close to 90 km/s, with approximately 10% of all systems showing v90 > 210 km/s at z=3. We show that a relative shortage of such high-velocity neutral gas absorbers in state-of-the-art galaxy formation models is a fundamental problem, present both in grid-based and particle-based numerical simulations. Using a series of numerical simulations of varying resolution and box size to cover a wide range of halo masses, we demonstrate that energy from gravitational infall alone is insufficient to produce the velocity dispersion observed in damped Ly-alpha systems, nor does this dispersion arise from an implementation of star formation and feedback in our highest resolution (~ 45 pc) models, if we do not put any galactic winds into our models by hand. We argue that these numerical experiments highlight the need to separate dynamics of different components of the multiphase interstellar medium at z=3.