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Abstract: We investigate the evolution of the galaxy merger rate predicted by twosemi-analytical galaxy formation models implemented on the MillenniumSimulation of dark matter structure growth. The fraction of merging galaxypairs at each time-step of the simulation is derived from the galaxy cataloguesobtained by the models and the results are compared with various observationalestimates of merger fractions taken from the literature. We find a good matchbetween the pair fractions derived from the simulation and the observedcounting of galaxy pairs obtained by different sources in the redshift range 0< z < 1.2. The predicted evolution of the number of galaxy mergers per Gyrgrows with redshift as an exponential rate proportional to 1+z^m, with mranging from 0.6 to 0.8 for 0 < z < 2, depending on the luminosity and massratios of the merging galaxies. Our results are in agreement with recentobservational results that argue for a flat evolution in the fraction of galaxymergers since z ~ 1.2. The weak evolution predicted for the galaxy merger ratein an hierarchical model universe shows that the mass assembly evolution ofgalaxies through mergers does not follow the rapid evolution of the halo mergerrate obtained in previous studies.

Autor: Abilio Mateus LAM

Fuente: https://arxiv.org/

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