Large-scale structures we see in the universe, such as galaxies,
galaxy clusters and structures beyond the scale of clusters, result from
gravitational instability of
almost isotropic and homogeneous density distribution
in the early universe. The degree of the initial anisotropy of the universe
and the subsequent growth of gravitational instability, coupled
with the expansion rate of the universe, determine the scale and abundance
of the structures formed in the universe at later times.
A galaxy survey directly observes a distribution of structures in
the sky using galaxies as a tracer of the underlying density distribution,
and yields constraints on cosmological models when compared to a
physical theory of structure formation based on a given cosmological model.
Among many cosmological and astronomical phenomena to be understood
from a galaxy survey, the nature of the observed accelerated expansion
of the universe is the most profound problem in the modern physics.
Motivated by various planned and on-going galaxy surveys,
including our own Hobby-Ebery Telescope Dark Energy eXperiment (HETDEX),
we show the way to fully exploit the data from a galaxy survey.
We improve a model of structure formation to include the effect
of baryonic pressure and the free-streaming of massive neutrinos at a mildly non-linear regime.
Future galaxy surveys are to reach the level of accuracy, where
the effect of massive neutrinos on the observed power spectrum is no longer negligible.
Proper understanding of these effects gives a way to measure
the absolute masses of neutrinos: one of the most fundamental particles,
which, by itself, will be a major development in the field of particle
physics.
Yet, most of the space (~80%) observed by galaxy surveys is
occupied by voids.
An ellipticity probability distribution function of voids
offers yet another way of probing cosmology.
Especially, a distribution of ellipticities in the redshift space
provides a unique way to measure a growth rate of the
structure in the universe apart from other cosmological parameters
when combined with the galaxy power spectrum. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/ETD-UT-2011-12-4568 |
| Date | 01 February 2012 |
| Creators | Shoji, Masatoshi |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Type | thesis |
| Format | application/pdf |
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