Detailed stellar populations of dwarf elliptical galaxies

This thesis consists of an observational study about the evolution of dwarf elliptical galaxies. Although these objects are numerically-dominant type of galaxies in the Universe, their origin and evolution still remain a matter of debate since they are intrinsically faint and their structure is very complicated. The objective of this thesis has been to determine detailed chemical abundances of many elements in the Virgo and Fornax cluster, which have never been studied before outside the Local Group, based on high spectral resolution observations obtained with large telescopes.

In this Ph.D thesis, we define the physical properties of dEs by focusing on their elemental abundances and stellar populations as analysed using integral field unit and long-slit spectroscopy. The aim of this work is to help a better and more complete understanding of star formation histories of dwarf ellipticals using abundance ratios. Chemical abundances provide us with information about the stellar populations. We determine abundance ratios of 37 dEs in the Virgo cluster. We present their ages, metallicity and abundance ratios for Na, Mg and Ca. We discuss their possible formation relations.  For various elements we want to investigate in detail their elemental abundance, so we need to high-resolution spectral indices. We define a new set of high-resolution indices, analogous to the Lick indices and investigate the dependence of the line indices on alpha enhancement. We perform a detailed stellar population of 8 dEs in Fornax cluster using the newly defined line indices of previous chapter and measured their abundance ratios.

Dissertation: http://hdl.handle.net/11370/cbadd2df-24a0-4f88-a122-2b062a16c035