Research Highlights

Convergence properties of halo merger trees and halo merger rates across cosmic time

In this work I present a method for building halo merger trees which are robust against pathologies introduced by errors or ambiguities in the halo finding process. The method builds matches using sorted lists of halo IDs and scans over a range of snapshots - both forwards and backwards in time - to construct halo progenitor lines. A detailed covergence study using the popular Subfind halo finder yields the optimal snapshot cadence and scan range for converged results. Merger rates are obtained for both friends-of-friends and substructure halos across most of observed cosmic time and galactic scales.

The Dynamical Lives of High Redshift Galaxies

The first paper presenting DRAGONS and the Tiamat Simulation Suite. We show how common relaxation metrics of halo relaxation behave (independantly of mass) in the early universe and demonstrate that fewer than 30% of galaxies are relaxed during the Epoch of Reionization.

Characterising Scale Dependant Bias

This paper presents and utilises the Gigaparsec WiggleZ (GiggleZ) simulation suite to characterise the scale dependance of galaxy clustering bias.

Probing the epoch of radiation domination using large-scale structure

This paper presents the first observational constraints on the scale of the turnover in the the large scale galaxy power spectrum. Forecasts are also presented for future (Euclid) and ongoing (BOSS) surveys.

The impact of mergers on relaxed X-ray clusters

Over a series of three papers, we use a suite of idealised 2-body hydrodynamic simulations to explore how X-ray and SZ morphologies, scaling relations and the properties of compact cool cores evolve during and after merger events.