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Investigating the high redshift universe with H-ATLAS

Pearson, Elizabeth 2014. Investigating the high redshift universe with H-ATLAS. PhD Thesis, Cardiff University.
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Abstract

Upon its completion the Herschel ATLAS (H-ATLAS) will be the largest submillimetre survey to date, detecting close to half-a-million sources. It will only be possible to measure spectroscopic redshifts for a small fraction of these sources. However, if the rest-frame spectral energy distribution (SED) of a typical H-ATLAS source is known, this SED and the observed Herschel fluxes can be used to estimate the redshifts of the H-ATLAS sources without spectroscopic redshifts. In this thesis, I use a subset of 40 H-ATLAS sources with previously measured redshifts in the range 0.5 < z < 4.2 to derive a suitable average template for high redshift H-ATLAS sources. I find that a template with two dust components (Tc = 23.9 K, Th = 46.9 K and ratio of mass of cold dust to mass of warm dust of 30.1) provides a good fit to the rest-frame fluxes of the sources in our calibration sample. I use a jackknife technique to estimate the accuracy of the redshifts estimated with this template, finding a root mean square of ∆z/(1 + z) = 0.26. For sources for which there is prior information that they lie at z > 1 we estimate that the rms of ∆z/(1 + z) = 0.12. I have used this template to estimate the redshift distribution for the sources detected in the H-ATLAS equatorial fields, finding a bimodal distribution with a mean redshift of 1.2, 1.9 and 2.5 for 250, 350 and 500 µm selected sources respectively. Using these redshifts I have estimated luminosity functions for the Phase 1 field. This has shown evidence of strong evolution out to a redshift of z ∼ 2. At which point luminosity evolution begins to slow until z ∼ 3, where it appears to stop altogether. Estimations of the angular correlation function showed strong clustering across most wavelengths and redshifts.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Uncontrolled Keywords: H-ATLAS, submillimetre survey, spectropic redshifts.
Funders: STFC
Date of First Compliant Deposit: 30 March 2016
Last Modified: 23 Oct 2023 15:27
URI: https://orca.cardiff.ac.uk/id/eprint/69524

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