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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 disengage fromthe global cosmological expansion. It is shown that the evolution of the slope of the power-law portion of the luminosity function at a constant mass-to-luminosity ratio observed in the Ultradeep 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. [ABSTRACT FROM AUTHOR]

We present the CIDA–UCM–Yale (Centro de Investigaciones de Astronomía, Universidad Complutense de Madrid, and Yale University) Survey (CUYS) for Hα+[N ii] 6549, 6584 Å emission-line galaxies (ELGs) using objective-prism spectra. The most important properties of a catalogue with 427 entries and significant subsets are analysed. The complete sample contains 183 statistically confirmed ELGs in a sky area of 151 deg2 and redshift up to 0.14. We determine the parameters of the Hα luminosity function using the Hα+[N ii] flux directly measured on the ELG spectra in this sample, and the star formation rate density derived is in agreement with values reported in the literature. Finally, we study the clustering properties of local star-forming galaxies relative to quiescent ones from different perspectives. We find that ELGs avoid dense regions of quiescent galaxies and we propose a power-law expression to parametrize the relation between star formation rate density and environment volume density of ELGs. [ABSTRACT FROM AUTHOR]