Cosmology with quasar spectroscopy

Download files
Access & Terms of Use
open access
Copyright: Zavarygin, Evgeny
Altmetric
Abstract
Quasar spectroscopy is a unique tool for cosmological studies. Passing through the Universe during billions of years, light from quasars contains information that in some cases cannot be collected in other types of measurements. The recent dramatic improvements in astronomical instrumentation and facilities allow increasingly stringent tests using large sets of high quality spectra. The available spectroscopic quasar data range from high resolution spectra of a relatively small number of objects down to low resolution spectra of a very large number of objects. In this thesis we make use of both types of data to test the standard ΛCDM cosmological model. We use a set of high resolution Keck/HIRES spectra of quasar Q1009+2956 to measure the deuterium abundance (D/H) at high redshift. The previous analysis of the z = 2.504 absorption system towards Q1009+2956 by Burles and Tytler yielded a D/H value greater than is predicted by other measurements. We repeat the analysis using an independent dataset of higher signal-to-noise. The deuterium absorption is found to be contaminated by a previously undetected blend. The analysis results in log D/H = -4.606 +/- 0.066, consistent with other measurements. Using a sample of 13 "reliable" D/H measurements we find the primordial deuterium abundance of (D/H)p = (2.545 +/- 0.025) x 10^-5, consistent with the prediction from the Planck cosmic microwave background analysis. We test the Cosmological Principle by measuring the cosmological distribution of neutral hydrogen over the redshift range 2 < z < 4, probed by the Ly-alpha forest. We use the largest dataset of low resolution quasar spectra available to date, from the SDSS/BOSS survey. A preliminary analysis indicates that a significant anisotropic signal spanning beyond the post-inflation causality scales appears to be present in the data. Taken at face value, this would suggest an anisotropic universe. However, a detailed study reveals sky position dependent systematics such that the data is in fact consistent with isotropy and hence with the standard ΛCDM cosmological model. A thorough investigation of a large number of potential systematic effects is presented. The results of that study should be beneficial in the design of the future large scale surveys such as DESI, 4MOST, WEAVE-QSO, and MSE.
Persistent link to this record
Link to Publisher Version
Link to Open Access Version
Additional Link
Author(s)
Zavarygin, Evgeny
Supervisor(s)
Webb, John
Flambaum, Victor
Creator(s)
Editor(s)
Translator(s)
Curator(s)
Designer(s)
Arranger(s)
Composer(s)
Recordist(s)
Conference Proceedings Editor(s)
Other Contributor(s)
Corporate/Industry Contributor(s)
Publication Year
2020
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
Files
download public version.pdf 29.26 MB Adobe Portable Document Format
Related dataset(s)