AbstractThis thesis describes a study into large scale structure cosmology with the dark energy survey and its use in sterile neutrino cosmology. Cosmological probes can be used to probe the nature of sterile neutrinos. Currently the most constraining data sets are from the cosmic microwave background (CMB) such as Planck. Low-redshift galaxy surveys that probe the large scale structure (LSS) can also be used to constrain neutrino properties but are currently limited by systematics. This thesis explores the CMB neutrino constraints, large scale structure systematics, and a combination of the large scale structure measurements and the CMB. I study the existing sterile neutrino constraints from the CMB and their comparison to oscillation experiments. I find that the CMB constraints from Planck are more constraining than many oscillation experiments. Planck is a complimentary probe of sterile neutrinos to the Main Injector Neutrino Oscillation Search (MINOS) experiment which is sensitive to low mass sterile neutrinos. However, the CMB constraints are model dependent and can be weakened by using a more complex model such as one with non-zero lepton asymmetry. I then study the clustering of galaxies in the Dark Energy Survey (DES) year 1 data, investigating the impact and mitigation of observational systematics. A number of correlations with observational properties are found and removed by applying weights to the galaxy sample. This method is tested for bias in parameter inference for both galaxy clustering alone, and in combination with DES weak lensing. I then present a simulated neutrino analysis combining simulated DES Y1 clustering and weak lensing signals with real data from the CMB and other cosmological probes. I use these measurements to constrain both massless and massive sterile neutrino models. I find that DES year 1 does not significantly add to the statistical power of a massless sterile neutrino analysis. However, the real data could tighten constraints by mitigating slight tensions between probes. The DES year 1 data, in combination with the CMB, baryon acoustic oscillations (BAO) and supernovae, are able to obtain constraints in a massive sterile neutrino model without the need for informative priors.
|Date of Award
|31 Dec 2018
|Sarah Bridle (Supervisor) & Joseph Zuntz (Supervisor)
- large scale structure
- weak gravitational lensing