Merger driven explosive evolution of distant galaxies (minor mergers)

Abstract

We derived solutions for the Smoluchowski kinetic equation for the mass function of galaxies, which describes mergers in differential approximation, where mergers with low-mass galaxies are the dominant factor. The evolution of the initial distribution is analyzed as well as the influence of the source represented by galaxies (halos) that separate from the global cosmological expansion. It is shown that the evolution of the slope of the power-law part of the luminosity function at a constant mass-to-luminosity ratio observed in the Ultra Deep Hubble Field can be described as a result of explosive evolution driven by galaxy mergers. In this case the exponent depends exclusively on the uniformity degree of merger probability as a function of mass. pacs: /, 95.30.Sf, 98.35.Ce, 98.62.Ck, 95.35

Star formation in nearby isolated galaxies

“…Thus the mergers seem to occur in groups and protoclusters inside larger-scale halos and also in the walls, filaments, and knots of the large-scale structure [27]. The interaction in the process of merging is purely gravitational and we therefore used the known galaxy merger probabilities in our estimates [20,25,26]. A proper description of observational data may mean that dark matter behaves as a collisional medium in the process of merging, as it was already pointed out in the literature (see references in [11] ).…”

“…can be reduced to a differential equation if the kernel function U (M 1 , M 2 ) is not singular at M 2 → 0, which is the case for galaxy mergers [20,25]…”

“…The Schechter LF slopes α (Fig. 1) determined in a series of papers by Bouwens, Illingworth, and their coauthors [4,5] , which we use below (see also numerous important references in [6,11,12,16,20] ), depend significantly on redshift. Note that the MF slope computed in hierarchical clustering models without the allowance for mergers [1,2,3] does not depend on z.…”

“…The uniformity index of the probability of galaxy mergers is known for the two extreme cases [20,25,26]. If the masses of merging galaxies are relatively small, then u = 2.…”