Conference paper
The Hydrodynamics of Galaxy Formation on Kiloparsec Scales
01 Jan 1993
Abstract
Two dimensional numerical simulations of Zeldovich pancake fragmentation in a dark matter dominated universe were carried out to study the hydrodynamical and gravitational effects on the formation of structures such as protogalaxies. Preliminary results were given in Yuan, Centrella and Norman (1991). Here we report a more exhaustive study to determine the sensitivity of protogalaxies to input parameters. The numerical code we used for the simulations combines the hydrodynamical code ZEUS-2D (Stone and Norman, 1992) which was modified to include the expansion of the universe and radiative cooling of the gas with a particle-mesh code which follows the motion of dark matter particles. The resulting hybrid code is able to handle highly nonuniform grids which we utilized to obtain a high resolution (« 1 kpc) in the dense region of the pancake. In a universe with 10% of its mass composed of hydrogen and helium of cosmic abundances and 90% of its mass in the form of dark matter, we set up a sinusoidal density perturbation of A. = 10 Mpc in the xl direction and small density fluctuations in the x2 direction at z=50. The perturbation amplitude in the xl direction is larger than the amplitudes of the fluctuations in the x2 direction so that the mass collapses in the xl direction and a pancake forms at z=5. We ran six runs of different resolutions and different amplitudes and types of initial density fluctuation in the x2 direction, and we find the following main results: (1) The gas density is about 10 times the dark matter density in the central region right after the pancake collapse at z = 5, but the gas and dark matter densities are about the same in the fragmented dense clump at z =0. (2) The gas overdensity is larger than the dark matter overdensity only in the shocked region, so the gas is biased over the dark matter only on the 68
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Details
- Title
- The Hydrodynamics of Galaxy Formation on Kiloparsec Scales
- Creators
- Joan M. Centrella - Drexel UniversityMichael Norman - University of Illinois at Urbana ChampaignWenbo Yuan Anninos - University of Illinois at Urbana Champaign
- Conference
- The Evolution of Galaxies and Their Environment
- Publisher
- National Aeronautics and Space Administration
- Resource Type
- Conference paper
- Language
- English
- Academic Unit
- Physics
- Identifiers
- 991022043493404721