Huetsi, Gert (2006): Cosmic sound: Measuring the Universe with baryonic acoustic oscillations. Dissertation, LMU München: Fakultät für Physik 

PDF
Huetsi_Gert.pdf 7MB 
Abstract
During the last ten to fifteen years cosmology has turned from a datastarved to a datadriven science. Several key parameters of the Universe have now been measured with an accuracy better than 10%. Surprisingly, it has been found that instead of slowing down, the expansion of the Universe proceeds at an ever increasing rate. From this we infer the existence of a negative pressure component  the socalled Dark Energy (DE)  that makes up more than two thirds of the total matterenergy content of our Universe. It is generally agreed amongst cosmologists and high energy physicists that understanding the nature of the DE poses one of the biggest challenges for the modern theoretical physics. Future cosmological datasets, being superior in both quantity and quality to currently existing data, hold the promise for unveiling many of the properties of the mysterious DE component. With ever larger datasets, as the statistical errors decrease, one needs to have a very good control over the possible systematic uncertainties. To make progress, one has to concentrate the observational effort towards the phenomena that are theoretically best understood and also least ``contaminated'' by complex astrophysical processes or several intervening foregrounds. Currently by far the cleanest cosmological information has been obtained through measurements of the angular temperature fluctuations of the Cosmic Microwave Background (CMB). The typical angular size of the CMB temperature fluctuations is determined by the distance the sound waves in the tightly coupled baryonphoton fluid can have traveled since the Big Bang until the epoch of recombination. A similar scale is also expected to be imprinted in the largescale matter distribution as traced by, for instance, galaxies or galaxy clusters. Measurements of the peaks in the CMB angular power spectrum fix the physical scale of the sound horizon with a high precision. By identifying the corresponding features in the low redshift matter power spectrum one is able to put constraints on several cosmological parameters. In this thesis we have investigated the prospects for the future widefield SZ cluster surveys to detect the acoustic scale in the matter power spectrum, specifically concentrating on the possibilities for constraining the properties of the DE. The core part of the thesis is concerned with a power spectrum analysis of the SDSS Luminous Red Galaxy (LRG) sample. We have been able to detect acoustic features in the redshiftspace power spectrum of LRGs down to scales of ~ 0.2 hMpc^{1}, which approximately corresponds to the seventh peak in the CMB angular spectrum. Using this power spectrum measurement along with the measured size of the sound horizon, we have carried out the maximum likelihood cosmological parameter estimation using Markov chain Monte Carlo techniques. The precise measurement of the low redshift sound horizon in combination with the CMB data has enabled us to measure, under some simplifying assumptions, the Hubble constant with a high precision: H_0 = 70.8 {+1.9} {1.8} km/s/Mpc. Also we have shown that a decelerating expansion of the Universe is ruled out at more than 5sigma confidence level.
Dokumententyp:  Dissertation (Dissertation, LMU München) 

Keywords:  cosmology, structure formation, acoustic oscillations, large redshift surveys, CMB, SZ clusters, cosmological parameters 
Themengebiete:  500 Naturwissenschaften und Mathematik
500 Naturwissenschaften und Mathematik > 530 Physik 
Fakultäten:  Fakultät für Physik 
Sprache der Dissertation:  Englisch 
Datum der mündlichen Prüfung:  30. Mai 2006 
1. Berichterstatter/in:  Sunyaev, Rashid 
URN des Dokumentes:  urn:nbn:de:bvb:1954005 
MD5 Prüfsumme der PDFDatei:  9cff2d1c7bf0058670e21565a3f2c53d 
Signatur der gedruckten Ausgabe:  0001/UMC 15435 
ID Code:  5400 
Eingestellt am:  20. Jun. 2006 
Letzte Änderungen:  19. Jul. 2016 16:20 