Large-scale structure as a probe of inflation and galaxy formation physics

Lead Research Organisation: Liverpool John Moores University
Department Name: Astrophysics Research Institute

Abstract

The distribution of matter on the largest scales and its evolution over time can be used to constrain cosmological models. Comparisons of existing large-scale structure measurements with those of the cosmic microwave background, which probes the Universe at early times, show mild evidence for tension. This tension can potentially be resolved by appealing to extensions of the standard model of cosmology and/or untreated systematic errors in the modelling of LSS, of which baryonic physics has been frequently suggested. We will revisit this tension using carefully calibrated cosmological hydrodynamical simulations, which thus capture the back reaction of the baryons on the total matter distribution. Furthermore, we will extend the BAryons and HAloes of MAssive Systems (BAHAMAS) simulations to assess the impact of uncertainties in the modelling of cosmic inflation. Inflation is an ad hoc addition to the hot big bang model that nicely accounts for many features of the observed Universe, however many of these successes are generic to inflation models of which there are many. Different models predict different amounts of deviation from a powerlaw in the initial power spectrum of density fluctuations. Through direct simulation and comparison to observations, we will provide rigorous constraints on the degree of so-called "running" of the primordial power spectrum spectral index and will assess whether non-standard inflation models can resolve the aforementioned tension.

Publications

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Pfeifer S (2020) The bahamas project: effects of a running scalar spectral index on large-scale structure in Monthly Notices of the Royal Astronomical Society

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Stafford S (2020) Exploring extensions to the standard cosmological model and the impact of baryons on small scales in Monthly Notices of the Royal Astronomical Society

Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/S505559/1 30/09/2018 29/09/2022
2159980 Studentship ST/S505559/1 30/09/2018 30/07/2022 Sam Stafford