2008/03/31 by Elena D’Onghia, E. D'Onghia, M. Mapelli +3 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.13625.x
Accepted for a publication on MNRAS. More references added and a comparison with previous works
arxiv created 2008/06/20 · openalex publication_date 2008/08/12 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We compare the observed merger rate of galaxies over cosmic time and the frequency of collisional ring galaxies (CRGs), with analytic models and halo merger and collision rates from a large cosmological simulation. In the Λ cold dark matter (ΛCDM) model, we find that the cosmic merger fraction does not evolve strongly between 0.2 ≤z≤ 2, implying that the observed decrease in the cosmic star formation rate since z∼ 1 might not be tied to a disappearing population of major mergers. Haloes hosting massive galaxies undergo on average ∼2 mergers from z≤ 2 up to present day, reflecting the late assembly time for the massive systems and the related down-sizing problem. The cosmic merger rate declines with redshift: at the present time, it is of a factor of 10 lower than at z∼ 2 in reasonable agreement with the current available data. The rate of CRG formation derived from the interactions between halo progenitors up to z= 2 is found to be a good tracer of the cosmic merger rate. In the ΛCDM model, the rate of CRGs as well as the merger rate do not scale as (1 +z)m as suggested by previous models. Our predictions of cosmic merger and CRG rates may be applied to forthcoming surveys such as GOODS and zCOSMOS.