1999/06/11 by W. J. Percival, Will J. Percival, L. Miller
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1999.02865.x
published as Mon.Not.Roy.Astron.Soc.309:823,1999 · 11 pages, 8 figures, accepted for publication in MNRAS
arxiv created 1999/06/11 · openalex publication_date 1999/11/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We calculate the rate at which dark matter haloes merge to form higher mass systems. Two complementary derivations using Press—Schechter theory are given, both of which result in the same equation for the formation rate. First, a derivation using the properties of the Brownian random walks within the framework of Press—Schechter theory is presented. We then use Bayes' theorem to obtain the same result from the standard Press—Schechter mass function. The rate obtained is shown to be in good agreement with results from Monte Carlo and N-body simulations. We illustrate the usefulness of this formula by calculating the expected cosmological evolution in the rate of star formation that is due to short-lived, merger-induced starbursts. The calculated evolution is well-matched to the observed evolution in ultraviolet luminosity density, in contrast to the lower rates of evolution that are derived from semi-analytic models that do not include a dominant contribution from starbursts. Hence we suggest that the bulk of the observed ultraviolet starlight at z>1 arises from merger-induced starbursts. Finally, we show that a simple merging-halo model can also account for the bulk of the observed evolution in the comoving quasar space density.