Non-linear relativistic effects on cosmological perturbations

Abstract

The next generation of galaxy surveys will be capable of determining cosmological parameters to an unprecedented precision. To yield the full scientific potential of such analyses, we require the appropriate theoretical descriptions. One observable of interest is the number density of galaxies.
This quantity is subject to various astrophysical effects which distort the observed image of galaxies away from where it would otherwise be observed in an unperturbed universe. We convert the real-space contributions to the galaxy number over-density to harmonic space where we take their angular correlations to find their associated bispectra. We present our code galbispectra and provide the results for its numerical evaluation of the dominant contributions to the angular galaxy bispectrum within the Newtonian limit (terms which dominate on scales less than the Hubble scale). In particular, we find that including the linear redshift space-distortion (RSD) and lensing convergence terms alongside Euclid-like magnification and galaxy bias parameters can significantly affect the magnitude of the angular galaxy bispectrum.

Date of Award	Aug 2021
Original language	English
Awarding Institution	University of Portsmouth
Supervisor	Robert Crittenden (Supervisor), Obinna Umeh (Supervisor) & David Wands (Supervisor)