University of Sussex
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The clustering of galaxies in the SWIRE survey

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posted on 2023-06-07, 15:22 authored by Mark Ian Frost
Despite the coherent cosmological framework provided by the ?CDM model that astronomers have to work within, there are still a lot of unanswered questions regarding galaxy formation and evolution. Measuring the clustering of galaxies can provide information about the different environments that different types of galaxies reside in. Also, measuring the clustering of similar samples of galaxies at different redshifts can provide insights into how galaxies have evolved over time. Previous clustering analyses, particularly at high redshift, have often been restricted to galaxy samples which are small, selected on observable properties and/or contain an unknown mixture of different spectral types. Small samples lead to limited statistics and the inability to break the sample into interesting subsamples based on properties, e.g. by luminosity or star formation rate. Selecting samples based on observable properties leads to varying intrinsic properties with redshift and hence makes interpreting the evolution of clustering difficult. Mixing spectral types makes it impossible to separate the contribution to the clustering signal from early and late-type galaxies which tend to cluster very differently. This thesis overcomes some of the limitations of earlier clustering analyses by using the Spitzer Wide area InfraRed Extragalactic (SWIRE) photometric redshift catalogue of Rowan-Robinson et al.(2008) to measure the clustering of galaxies. The SWIRE catalogues covered multiple fields and large volumes providing large samples of galaxies over 0.1 < z < 1.5. The template fitting procedure also provides spectral classifications as well as intrinsic properties such as stellar mass and star formation rate estimates. The clustering of elliptical and spiral galaxies detected in SWIRE is measured as a function of stellar mass over 0.1 = z = 1.5. The clustering of spiral galaxies selected on star formation rate is also investigated over the same redshift range. Such measurements can help constrain theories of galaxy evolution. Another Spitzer dataset, the dark field, is used in an attempt to place one of the first observational constraints on the detection rate of population III supernovae. The dark field is an extragalactic data set with repeat imaging on a monthly basis over a baseline of approximately 2 years. The unprecedented depth and multi-epochal nature of this data makes it ideal for a first foray into trying to detect supernovae from the first stars.


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  • doctoral

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  • eng


University of Sussex

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