dc.contributor.author Oldham, Lindsay Joanna dc.date.accessioned 2017-10-31T15:33:12Z dc.date.available 2017-10-31T15:33:12Z dc.date.issued 2017-09-01 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/267989 dc.description.abstract In this thesis, I develop and combine strong lensing and dynamical probes of the mass of early-type galaxies (ETGs) in order to improve our understanding of their dark and luminous mass structure and evolution. Firstly, I demonstrate that the dark matter halo of our nearest brightest cluster galaxy (BCG), M87, is centrally cored relative to the predictions of dark-matter-only models, and suggest an interpretation of this result in terms of dynamical heating due to the infall of satellite galaxies. Conversely, I find that the haloes of a sample of 12 field ETGs are strongly cusped, consistent with adiabatic contraction models due to the initial infall of gas. I suggest an explanation for these differences in which the increased rate of merging and accretion experienced by ETGs in dense environments leads to increased amounts of halo heating and expansion, such that the signature of the halo's initial contraction is erased in BCGs but retained in more isolated systems. Secondly, I find evidence that the stellar-mass-to-light ratio declines with increasing radius in both field and cluster ETGs. With M87, I show that the strength of this gradient cannot be explained by trends in stellar metallicity or age if the stellar initial mass function (IMF) is spatially uniform, but that an IMF which becomes increasing bottom-heavy towards the galaxy centre can fully reproduce the inference on the stellar mass. Finally, I use the sizes, stellar masses and luminous structures of two samples of massive ETGs at redshift $z\sim0.6$ to set constraints on the mechanisms of ETG growth. I find that ETGs in dense cluster environments already lie on the local size-mass relation at this redshift, contrary to their isolated counterparts, and suggest that this may be evidence for their accelerated growth at early times due to the higher incidence of merger events in clusters. I also show that massive compact ETGs at this redshift are composed of a compact, red, spheroidal core surrounded by a more extended, diffuse, bluer envelope, which may be a structural imprint of their ongoing inside-out growth. Overall, the studies presented in this thesis suggest a coherent scenario for ETG evolution which is dominated by hierarchical processes. dc.description.sponsorship STFC dc.language.iso en dc.rights No Creative Commons licence (All rights reserved) dc.rights All Rights Reserved en dc.rights.uri https://www.rioxx.net/licenses/all-rights-reserved/ en dc.subject Galaxy evolution dc.subject Dark matter dc.subject Strong gravitational lensing dc.title The evolution of dark and luminous structure in massive early-type galaxies dc.type Thesis dc.type.qualificationlevel Doctoral dc.type.qualificationname Doctor of Philosophy (PhD) dc.publisher.institution University of Cambridge dc.publisher.department Institute of Astronomy dc.date.updated 2017-10-30T17:01:24Z dc.identifier.doi 10.17863/CAM.13920 dc.publisher.college Corpus Christi dc.type.qualificationtitle PhD in Astronomy cam.supervisor Auger, Matthew cam.supervisor Evans, N Wyn rioxxterms.freetoread.startdate 2017-10-30
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