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Towards precision measurements of large-scale structure with next-generation spectroscopic surveys

Farr, James Alexander; (2021) Towards precision measurements of large-scale structure with next-generation spectroscopic surveys. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Over recent decades, spectroscopic surveys have yielded exceptional measurements of the large-scale structure of the Universe. Notably, they have measured the baryon acoustic oscillation (BAO) scale at late times, helping to develop a tightly-constrained cosmological model by complementing measurements from the cosmic microwave background. In this thesis, we focus on late-time BAO measurements from quasar (QSO) spectra. Such measurements can be made at 1<z<2 via direct QSO clustering, and at 2<z<4 via the Lyman-alpha (Lya) forest extracted from high-z QSO spectra.In the near future, the Dark Energy Spectroscopic Instrument (DESI) will continue to advance this field, increasing the quantity and quality of QSO spectra available via a host of technological improvements. In order to maximise the impact of its data, however, DESI will require major advances in analysis methods to be made. This thesis describes work to develop such methods for use in two areas of DESI’s QSO survey. First, we address the construction of optimal strategies for classifying QSO target spectra. We use data from existing surveys to demonstrate the performance of potential strategies, finding that high performance levels can be achieved using existing classification tools. Next, we present LyaCoLoRe, a package developed to produce mock Lya forest datasets from simple simulations, to be used in Lya BAO analyses. We describe the methods employed by LyaCoLoRe, and demonstrate that our mocks are suitable to be used in Lya BAO studies present and future. We then discuss applications of the classification strategies and mock datasets presented previously, as well as a method of using BAO measurements to constrain the local cosmic expansion rate, showing results from current datasets and providing forecasts for DESI. We conclude by highlighting a number of future paths which our work could follow, with particular focus on the opportunities that will emerge from DESI.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Towards precision measurements of large-scale structure with next-generation spectroscopic surveys
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10119700
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