| This dissertation investigates the numerics and physics involved in incorporating a baryonic species into simulations of cosmological structure formation. I begin by describing a new numerical hydrodynamic technique known as Adaptive Smoothed Particle Hydrodynamics, or ASPH. ASPH is a modified form of Smoothed Particle Hydrodynamics (SPH), designed to allow resolution scales to adapt to locally anisotropic density evolution, thereby maximizing the potential resolution of a simulation.; Next a series of 2-D simulations of an idealized cosmology is presented, incorporating both baryons (10% by mass) and dark matter (90% by mass), varying both the resolution and input perturbations. These models only converge with increasing resolution once the relevant Jeans scale is resolved. Additionally, it is demonstrated that the resolved, collapsed structures tend to have baryon enriched cores which are embedded in dark matter halos, even without accounting for radiative cooling.; Next, hierarchical structure formation based on scale free initial conditions is analyzed using a set of 3-D models without radiative cooling. The evolution is expected to be self-similar in time, and under certain restrictions the expected scalings are identified in these experiments. The temperatures and luminosities of the groups are tightly correlated with the baryon masses, and these relations are well-represented by power-laws. The Press-Schechter (PS) mass distribution predicts the overall group dark matter and baryon masses fairly well, though PS may somewhat overpredict the baryon masses. Combining the PS mass distribution with the measured relations for {dollar}T(M){dollar} and {dollar}L(M){dollar} predicts the temperature and luminosity distributions well.; Finally, a set of 2-D scale-free models with radiative cooling is considered. For a variety of initial density perturbation spectra and cooling laws, the dissipated baryon objects obey the expected self-similar scaling relations reasonably well, in fact almost as well as the cases without radiative cooling. It also appears that simple scaling arguments reasonably predict the fraction of cooled gas which forms in an object as a function of mass. Overall these results are encouraging both for the use of numerical models to study galaxy formation, as well as supporting the use of semi-analytic techniques to study the evolution of such dissipated structures. |
