Weak Lensing from Galaxies, Clusters and Super-clusters in Numerical Simulations

  • Aaron Peters

Student thesis: Phd

Abstract

This thesis investigates several issues associated with the numerical modelling of the weak lensing signal by galaxies, clusters and super-clusters. We use a combination of full hydrodynamic and dark matter only simulations to investigate the effect that baryonic physics and selecting super-cluster regions have on the matter power spectrum. On large scales we find that the matter power spectrum measured from our super-cluster sample has at least twice as much power as that measured from our random sample. Our investigation of the effect of baryonic physics on the matter power spectrum is found to be in agreement with previous studies and is weaker than the selection effect over the majority of scales. We also investigate the effect of targeting a cosmologically non-representative, super-cluster region of the sky on the weak lensing shear power spectrum. We frame our results within the context of the Super-CLuster Assisted Shear Survey (Super-CLASS), and find that the convergence power spectrum measured from our super-cluster sample has a larger amplitude than that measured from the random sample on all scales. In addition, we generate and validate a mock radio weak gravitational lensing catalogue, suited for cosmic shear, galaxy-galaxy lensing and cluster lensing studies. In the penultimate chapter, we use this catalogue to investigate the evolution of the concentration-mass relation of dark matter haloes. We estimate the concentrations and masses with two approaches. In the first approach, we fit NFW models to density and surface mass density profiles that are measured directly from the simulation's particle data. For the second approach, we fit NFW models to shear profiles that we measure from the catalogue's shear fields. The inferred concentration-mass relations are found to be in good agreement with previous studies, particularly those obtained from the density and surface mass density profiles. Finally, we anticipate that the mock catalogue we have produced will also prove useful in evaluating the performance of radio weak lensing analyses with future radio surveys, e.g. the Square Kilometre Array.
Date of Award31 Dec 2019
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorScott Kay (Supervisor) & Michael Brown (Supervisor)

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