Sedgwick, TM (2021) Probing Fundamentals of Galaxy Evolution and Cosmology Using Supernovae. Doctoral thesis, Liverpool John Moores University.

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Abstract

Supernovae are the explosive and luminous ends of life for a variety of types of star. They exhibit a wide diversity of light-curve shapes and chemical abundances as a function of their type. The physics of supernova explosions is one topic of ongoing research, particularly the mechanisms by which supernovae expel their outer layers and create remnants such as black holes and neutron stars. There is also much to be learnt about the progenitor stars of supernovae, from observing, for instance, the sites of SN explosions in pre-supernova imaging. Such a comparison of progenitor and supernova properties yields a direct picture of the end of the stellar evolutionary process. Supernovae also show fundamentals of nuclear and particle physics acting on human timescales and thus are perfect test-beds for such areas of science. However, what is of most interest in this thesis is the connection between supernovae, galaxy evolution, and our Universe's cosmology. This thesis presents novel techniques using supernovae as probes of galaxy evolution and cosmology. The tight connection between core-collapse supernova rates and star formation rates is firstly exploited to make significant contributions to 2 outstanding problems in the area of galaxy evolution: Core-collapse supernovae are used to probe the sub-structure problem, or the surplus of observed low-mass galaxies relative to the number predicted by simulations invoking a Λ-CDM cosmology, by detecting previously missed low surface brightness galaxies at these supernova positions and by utilising the relationship between the volumetric star formation rate density, specific star formation rate and the galaxy stellar mass function. These supernova rates are then utilised to measure the mean star formation rates of elliptical galaxies. It is currently unknown whether these galaxies are entirely quiescent or are instead maintaining a hard-to-measure low level of star formation at current epochs. Many Λ-CDM simulations predict that the latter is the case, due to the ongoing influence of minor mergers. Finally, the predictable luminosities of Type Ia supernovae are exploited for their use as `standard candle' distance indicators, allowing definitive tests to be made for the effects of supernova environment on local measurements of the current rate of expansion of our Universe.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Supernovae; Galaxy Evolution; Galaxy Formation; Cosmology; Statistical Methods; Star Formation; Dwarf Galaxies; Low Surface Brightness Galaxies; Elliptical Galaxies; Observational Astrophysics; Mass Function; Luminosity Function
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Date Deposited:	24 Nov 2021 12:34
Last Modified:	13 Sep 2022 14:11
Supervisors:	Baldry, I and James, P
URI:	https://researchonline.ljmu.ac.uk/id/eprint/15824

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