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Title: An investigation of galaxy evolution with H-ATLAS and gravitational lenses
Author: Amvrosiadis, Aristeidis
ISNI:       0000 0004 8500 8246
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2019
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This thesis presents a collection of studies which mainly focus on the population of high-redshift dusty star-forming galaxies (DSFGs) in the context of galaxy evolution. The sample of DSFGs that is used in this thesis was discovered as part of the Herschel-Astrophysical Terahertz Large Area Survey (HATLAS; Eales et al., 2010) which is the largest area extragalactic survey undertaken with the Herschel Space Telescope. One Chapter of this Thesis studies the clustering statistics, i.e. the angular correlation function (ACF), of this population demonstrating that when selected on the basis of their flux density (i.e. S250¹m È 30 mJy) they exhibit a higher clustering strength at high redshift (z È 1; r0 Æ 8¡14 Mpc/h) than at low redshfit (z Ç 0.3; r0 Æ 1¡2 Mpc/h). From a galaxy evolution point of view this it is evident that we are dealing with two different galaxy populations, where the later is consistent with being the progenitors of massive early-type galaxies in the local Universe. This study uses that largest sample of DSFGs (discovered in the H-ATLAS survey) that has even been used to perform the measurement of their ACF. Another Chapter of this Thesis studies the properties of the Interstellar medium (ISM) of one of these high redshift DSFGs (HATLAS J091043.0¡000322) using a suite of multiwavelength observations. As this object is strongly lensed, we combined the resolving power of (ALMA) with the enchanced resolution offered by strong lensing to probe scales down to 300¡700 pc. Our morphological and kinematical analysis of the ISM components led us to conclude that this object is more likely undergoing a major-merger event. Finally, another chapter of this thesis utilizes a sample of Herschel-selected strongly-lensed galaxies to study the density profiles of the lens population in a statistical manner. Using both numerically and analytically-derived density distributions we were able to reproduce the observed distribution of image separations. Although we were not able to distinguish between the two profiles, we showed that with a sample »200 lenses that would become possible, highlighting that the simplicity of our selection of our sample does not introduce any additional systematics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QB Astronomy