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Session 30 - Galaxy Evolution I.
Oral session, Monday, January 15
1st Floor, La Villita Assembly Building
We will discuss how one can solve the faint blue galaxy problem and possibly constrain cosmological parameters using high resolution galaxy images. Different galaxy evolution models predict their own unique relations between various properties such as sizes, morphologies, colors, redshifts, and pair statistics. The comparison of observational data from HST Medium Deep Survey (MDS) with these predictions shows that ; 1) The faint blue galaxies are most likely to be dominated by dwarf galaxies and irregular galaxies that are undergoing strong luminosity evolution at moderate redshift. 2) Galaxies such as giant ellipticals and normal spirals do not show indications of strong evolution, but shows indication of the mild passive luminosity evolution. The mechanism for the strong luminosity evolution of dwarf or irregular galaxies is uncertain. However, the major merging process (the merging between galaxies with similar or equal masses) can be excluded as a candidate of this mechanism, according to the size distribution of giant ellipticals. Since the evolution of the giant ellipticals are found to be dominated only by its passive luminosity evolution, possible tests on Ømega and \Lambda using giant ellipticals are discussed. A measurement of the Ømega using the number counts of ellipticals and the strong gravitational lenses prefer the universe with low Ømega or non-zero cosmological constant \Lambda to the Ømega_matter = 1 universe.
