Mass estimation, dynamics and feedback in galaxy groups

Pearson, Richard John (2015). Mass estimation, dynamics and feedback in galaxy groups. University of Birmingham. Ph.D.

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Abstract

Accurate mass estimates for galaxy groups and clusters are important for understanding the evolution of matter within the universe. In this thesis we first discuss methods of mass estimation currently used within the literature, and introduce a set of scaling relations for mass estimation in cases where literature methods are not applicable. We find that methods based on group richness provide the best (i.e. lowest scatter) mass estimator.
Secondly, we study the impact of feedback on hot group gas for a sample of optically selected groups. We refine the group selection using their dynamical state, identified through substructure in the distribution of member galaxies. We find this sample to be underluminous compared to an X-ray selected sample. Furthermore, with two groups showing high 2σ lower limits on entropy, the population of high entropy groups predicted by hydrodynamical simulations may have been detected.
Finally, we combine measures of dynamical state and mass estimation scaling relations to understand how the presence of substructure can impact upon the ability to reliably estimate group and cluster masses. We find that substructure introduced through poor group identification has the largest effect on the quality of the final mass estimates.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):