Other
Scientific paper
Aug 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003phdt........12l&link_type=abstract
Thesis (PhD). THE JOHNS HOPKINS UNIVERSITY, Source DAI-B 64/02, p. 764, Aug 2003, 198 pages.
Other
3
Scientific paper
The formation of stars in the smallest galaxies is an important test of the standard paradigm for galaxy formation and evolution. While reasonably successful otherwise, current simulations of hierarchical galaxy formation have great difficulty reproducing the number density, star-formation histories, and structural parameters of local dwarf galaxies. Motivated by these difficulties, we use the observations of both the local dwarf galaxy population and the progenitors of dwarf galaxies in the distant universe, and a new approach to testing galaxy evolution, to trace the evolution and star-formation histories of dwarf galaxies. In the first half of this thesis, we present the results of an HST survey of ˜ 70 dwarf elliptical galaxies (dEs) in the nearby Virgo and Fornax Clusters. By resolving the globular clusters and nuclei from the underlying stars in each dE, we use these three sub- populations to trace the dE star-formation histories. We find that the dE globular cluster candidates are as blue in V I as the metal-poor globular clusters of the Milky Way. The observed correlation of the dE globular cluster systems' V I color with the luminosity of the host dE is strong evidence that the globular clusters were formed within the halos of dEs, and do not have a pre-galactic origin. The blue V I colors of the globular cluster systems and nuclei relative to the dE stellar envelopes require at least two separate star- formation episodes within the dEs. We explore the possibility that many of the dE nuclei are dynamically decayed massive globular clusters. However, we find that dynamical friction appears to be too effective at destroying globular clusters to account for the faint nuclei and the cluster systems observed in low-luminosity dEs, unless the clusters are relatively young or the dEs possess extended dark-matter halos. The extremely blue colors of two nuclei indicate younger ages than the dE stellar halos and globular cluster systems. In the second half of this thesis, we develop a Bayesian relative maximum likelihood approach to quantitatively test galaxy evolution models against multi-wavelength galaxy surveys, and use this method to test dwarf galaxy evolutionary scenarios against the Hubble Deep Field North and the Sloan Digital Sky Survey Early Data Release. This technique simultaneously fits the observed colors, luminosities, and redshift distributions in a self-consistent manner and incorporates the effects of selection biases. Assuming giant galaxies evolve passively at redshifts < 1, we attempt to constrain when dwarf galaxies formed the bulk of their stars and on what timescales. Given our straight-forward assumptions, we find that the data are best matched by a relatively late epoch (at redshift ˜ 1) for the on-set of major star-formation in dwarf galaxies, with the dwarfs forming the majority of their stars in short bursts at that epoch. This is consistent with the V I colors of the Virgo and Fornax dE stellar halos. However, direct comparison of the predictions of our “best-fitting”model to the data indicate that our models are overly simple. We discuss the implications for the evolution of dwarf galaxies, and future prospects for Bayesian tests of galaxy evolution.
No associations
LandOfFree
The history of the evolution of dwarf galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The history of the evolution of dwarf galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The history of the evolution of dwarf galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1510856