The history of galaxy formation as a cosmological probe

Abstract

As galaxy formation and evolution over long cosmic time-scales depends to a large degree on the structure of the universe thus the assembly history of galaxies is potentially a powerful approach for learning about the universe itself. As the first step we will present the predicted merger history of dark matter haloes based on the Extended Press-Schechter formalism as a function of cosmological parameters, redshift and halo mass. We calculate how major halo mergers are influenced by changes in the cosmological values of Ωm, ΩΛ, σ8, the dark matter particle temperature (warm versus cold dark matter), and the value of a constant and evolving equation of state parameter w(z). We find that the merger fraction at a given halo mass varies by up to a factor of 3 for haloes forming under the assumption of cold dark matter, within different underling cosmological parameters. Using galaxy mass to halo mass relations we find that the current measurements of the merger history, as measured through observed galaxy pairs as well as through structure, are in agreement with the concordance cosmology. We discuss this implications for this, and the future observations which which will put better limits on using galaxy formation as a probe of cosmology.