München 2019 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 10: Astrophysics II: Galaxies and Cosmology
EP 10.3: Vortrag
Freitag, 22. März 2019, 11:30–11:45, HS 19
The galaxy merger rate from Emerge, an empirical model for galaxy formation — •Joseph A. O’Leary1, Benjamin P. Moster1,2, and Thorsten Naab2 — 1Universitäts-Sternwarte, Ludwig-Maximilians-Universität, München, Germany — 2Max-Planck Institut für Astrophysik, Garching, Germany
The galaxy-galaxy merger rate is a critical component in constructing a complete picture of galaxy formation and evolution. We explore the galaxy-galaxy major merger rate in the frame work of the empirical model for galaxy formation, Emerge. Here we define the rate, R as the percentage of galaxies that will merge with another similar sized galaxy (mass ratio 1:4) within some time interval. We find that between 2% and 8% of large galaxies (M* > 1010 M⊙) will experience a major merger per Gyr. Generally, our results exhibit an increase in rate with increasing redshift up to z≈1, followed by a rapid decay at higher redshifts. The rates we determined through our model tend to be lower when compared with other theoretical models. However, we generally find very good agreement with recent observations, although the rates derived from our model tend to be flatter. Finally, we show that merger rates computed from close galaxy pairs, as done for observed rates, over predict the true intrinsic rates by a factor of 3. This discrepancy has direct consequences for the interpretation of observed galaxy merger rates.