Theoretical Cosmology

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

We have a broad brush picture of the evolution of the Universe which has consistently stood up to experimental and observational scrutiny. With Einstein's theory of gravity we are able to explain the expansion of recession of galaxies, the presence of a residual bath of relic radiation and the rough abundances of the light elements. Within the auspices of this grant we wish to subject this model to more detailed scrutiny and in doing so, construct a detailed understanding of the physical processes that come into play on an immense range of scales. On the various largest scales, we can use the roughness in the relic radiation to extract the information about the nature of space time and energy when the Universe was in it infancy. Specifically we can now try and detect the background of ripples in space-time, called gravity waves, by looking for particular distortions in relic light. To do so, we must come up with clever algorithms that can cope with the extremely large data sets and extract weak signals. It will be necessary to separate out what is truly due to the gravity waves from other sources of radiation which will contaminate the signal. With such precise data sets, and including other cosmic observables such as the way that galaxies move towards or away from each other, it should be possible to probe and peruse our standard theory and see if there is any evidence for deviations from it. This holistic approach will also allows us to learn more about the nature of the matter and energy that fills the Universe. On smaller scales, we must focus on the building blocks of structure: galaxies. These are extremely complex organisms that a host a wide range of physical process from gravitational to chemical. We will tackle this problem in a variety of ways. At the smallest scales we will work with extremely accurate numerical models of how the different physical process occur and how they trigger the formation of stars. These are complemented by analytical models which are technically much simpler but will allow us to explore a much wider range of environments, from now all the way back to the past when the Universe is much denser and hotter. There is now compelling evidence that there very massive black holes inhabiting at the centres of galaxies. We wish to study this novel and unique observational phenomena and study its theoretical implications. In particular we wish to, once again, study how the existence of black holes drives the formation and evolution of galaxies and how their presence may be tested in a number of observational ways.

Publications

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BaƱados M (2010) Eddington's theory of gravity and its progeny. in Physical review letters

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Clifton T (2009) Errors in estimating O ? due to the fluid approximation in Journal of Cosmology and Astroparticle Physics

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Clifton T (2012) Modified gravity and cosmology in Physics Reports

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Clifton T (2009) What the small angle CMB really tells us about the curvature of the Universe in Journal of Cosmology and Astroparticle Physics

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Codis S (2013) Connecting the cosmic web to the spin of dark haloes: implications for galaxy formation in Monthly Notices of the Royal Astronomical Society

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Davis O (2011) Most massive haloes with Gumbel statistics Most massive haloes with Gumbel statistics in Monthly Notices of the Royal Astronomical Society

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Desmond H (2018) Reconstructing the gravitational field of the local Universe in Monthly Notices of the Royal Astronomical Society