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Session 94 - Large-Scale Structure: Observations and Theory.
Oral session, Wednesday, January 17
Corte Real, Hilton

[94.05] Hydrodynamical Cosmological Simulations of Large Scale Structure

J. M. Owen (OSU)

The incorporation of hydrodynamics within cosmological simulations allows for more direct comparison of simulation results with observations (in comparison with purely gravitational studies), as this allows the dissipative baryonic component of the cosmological gas to be followed with some confidence. In particular, such studies promise to evolve and follow a population of cold, collapsed baryonic structures which can be identified as ``galaxies'', an important advance as galaxies represent the primary observational tracers of large scale structure in the universe. My collaborators and I have developed a new form of Smoothed Particle Hydrodynamics known as Adaptive Smoothed Particle Hydrodynamics (ASPH) for use in cosmological structure formation simulations. ASPH's principal advantage is that it allows resolution scales within the simulation to fully adapt to anisotropic evolution of the density field, an important feature for cosmological investigations since anisotropy is a generic feature of gravitational collapse scenarios. However, before an ambitious simulation (such as an attempt to follow a realistic cosmological model complete with galaxy formation) can be attempted, it is important to both thoroughly characterize the numerical tools being used as well as understand the underlying physics. To this end I have extensively tested the ASPH technique on a variety of problems. I have also performed a series of simplified cosmological models designed to study specific questions about the influence of a dissipative baryonic species on the development of large scale structure. One such issue is the effect of having a finite pressure in the system, leading to a minimum Jeans mass for the baryons. I will discuss the results of such an investigation for a variety Jeans masses and cutoffs in the initial density fluctuation power-spectra. The goal of this work is to model structure formation under a low Ømega cosmology, with an emphasis upon tracking the evolution of a population of galaxies.

Program listing for Wednesday