Cosmoparticle Constraints with Large-Scale Structure
Precisely measuring the large-scale structure of the universe is key to learning about fundamental physics. This thesis focuses on two of the most pressing problems in fundamental physics; massive neutrinos and dark energy, and explores what can be learnt from precise measurements of the large-scale structure of the universe.First, I examine the precision required for large-scale structure measurements to determine the neutrino hierarchy when combined with current particle physics results. The neutrino hierarchy refers to the ordering of the neutrino masses, and is a key question in neutrino physics. Particle physics and cosmology provide complementary information about neutrinos so a joint analysis is highly desirable. However, the method of incorporating prior knowledge about neutrinos into the analysis can strongly influence any results. I therefore developed a prior which is agnostic to the hierarchy by design, and used it to set a conclusive target precision for upcoming cosmological experiments. Second, I forecast whether including weak lensing magnification in future large-scale structure analyses can improve the constraints on dark energy and dark matter. Weak gravitational lensing is one of the key probes in forthcoming galaxy surveys, such as the Vera Rubin Observatory. Usually, the signal is detected by measuring distortions to the shapes of millions of galaxies - weak lensing shear. However, it can also be detected by measuring fluctuations in the number density of galaxies across the sky - weak lensing magnification. Weak lensing magnification only requires a count of galaxies to be made, as opposed to a measurement of their shape so is therefore traceable even for the very faint, small, and distant galaxies. In this thesis, I determined whether including weak lensing magnification in upcoming deep large-scale structure analyses improves the final cosmological constraints.
- Pub Date:
- December 2020