Constraining cosmological and galaxy formation models from galaxy surveys

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Observations appear to show that the Universe is not only expanding, but that it is doing so at an accelerating rate. Two explanations have been proposed to understand this: (i) the accelerated expansion is caused by some form of 'dark energy' [including a cosmological constant), or (ii) Einstein's law of gravity {GR) needs to be modified on cosmological scales. Many surveys have been attempting to measure the equation of state, w, of dark energy; all results so far are consistent with w = -1, as expected for a cosmological constant. In this project the student will explore alternative ways of constraining cosmological and galaxy formation models utilising existing and future galaxy surveys. The goal Is to design observational tests that can distinguish between different models, verified using numerical simulations. These tests might include galaxy dynamics, as Inferred from redshift-space distortions of the clustering signal, cross-correlation of optimally-weighted galaxy samples, and cross-correlation with other surveys, such as radio surveys for neutral hydrogen. The student will then apply these tests to existing survey data, such as the Galaxy and Mass Assembly survey (GAMA; http://www.gama-survey.org/), and inform the design of future surveys to be carried out with major new facilities such as the 4-metre Multi-Object Spectroscopic Telescope (4MOST; https://www.4most.eu/J and the Large Synoptic Survey Telescope (LSST; https://www.lsst.org). This project will give the student experience in numerical simulations and state of the art observational data-sets as well as getting closely involved in major new surveys.