In this thesis, I probe the stellar and dark matter component of galaxies in order to infer their evolutionary histories. I am doing this by studying two distinct galaxy population samples: (i) a high redshift sample at z∼1, and (ii) a high density environment sample of galaxies in the nearby Coma cluster. By comparing these samples to a sample of galaxies in the local Universe in a low density environment, I infer variation in their properties as a function of time and environment. For both samples, I create accurate dynamical models to infer the stellar Mass-to-Light ratios of the galaxies and their dark matter fractions. Furthermore, I model the stellar population of the galaxies using a full-spectrum technique while reproducing their star formation history in a non-parametric manner. In addition, I use IFS data for a subset of galaxies in the high density sample to create detailed dynamical models that strengthen the results found in that sample. Based on the quantities derived from these analyses, I present results on the IMF normalisation and dark matter fraction of galaxies in both samples. Furthermore, I studied the scaling relations of these galaxies and compared them to that observed for the ATLAS^3D sample, which serves as a low density sample of the Local Universe, to infer variation in galaxy properties as a function of time and environment.

Thesis (doctoral)--Tartu University, 2006. / Includes bibliographical references (54-61).

Stellar feedback processes have been suggested as a mechanism for explaining various properties of galaxies, especially dwarf galaxies, which have weaker potentials and thus lower escape velocities for galactic winds. In this thesis, I present work done during my DPhil to better understand these processes. I begin by discussing the techniques used to simulate galaxies as collections of astrophysical fluids in a cosmolog- ical context, and present some methods for interpreting the results of such simulations. I then present two projects aimed at furthering our understanding of feedback in dwarf galaxies. The first project is the investigation of a suite of simulations of satellites of a Milky Way-class halo. We discuss the formation of high-redshift dwarf galaxies and the effect that supernova feedback and reionisation have on the gas content and star formation history of these objects. We find that neither process has a dramatic effect on the star formation rates in high redshift dwarf galaxies that have already begun forming stars prior to reionisation. We do find, however, that the population of satellites is dramatically altered by the presence of cooled gas in the host halo, which increases the tidal stripping of satellites that pass close to the host. The second project concerns detailed simulations of a 15 solar mass star throughout its evolution, studying photoionisation, wind and supernova feedback from this star in various environments. Preliminary results are given for these simulations, which are compared to the results of previous authors.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xiv, 250 p.; also includes graphics (some col). Includes abstract and vita. Advisor: Terry Walker, Dept. of Physics. Includes bibliographical references (p. 227-250).

Thesis (Ph. D. in Physics)--Vanderbilt University, May 2010. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Physics and Astronomy." Includes bibliographical references.

In this thesis I present new interferometric ¹²CO observations of 30 early-type galaxies (ETGs). These galaxies were the brightest ~2/3 of CO detected ETGs from the complete, volume limited Atlas^3D survey. By including literature data I construct the largest ever sample of mapped ETGs, containing 41 objects, and use this sample to analyse the morphology, kinematics and origin of the molecular gas. Many of the galaxies in this sample have relaxed molecular discs, but polar structures, rings, bars and disturbed gas distributions are also present. Around half of the galaxies have molecular gas that follows the stellar light profile, similar to molecular gas in spirals, while others have molecular gas excesses, truncations, rings or composite profiles. The molecular gas extent is smaller in absolute terms in ETGs than in late-type galaxies, but the size distributions are similar once scaled by the galaxies optical/stellar characteristic scalelengths. Cluster environments, however, lead to systems having denser, more compact molecular reservoirs. I find that molecular gas is an excellent kinematic tracer, even in high-mass ETGs, and thus molecules may be the kinematic tracer of choice for probing the M/L evolution of galaxies over cosmic-time. I use this knowledge to construct the first ever early-type CO Tully-Fisher relation, and show that it is offset from the Tully-Fisher relation of spirals by 0.98±0.22 magnitudes at Ks-band. I find that a third of my sample galaxies have their molecular and ionised gas kinematically misaligned with respect to the stars, setting a strong lower limit on the importance of externally acquired gas (e.g. from mergers and cold accretion). The origin of the molecular gas seems to depend strongly on environment, with externally acquired material being common in the field but nearly completely absent in Virgo. Furthermore, my results suggest that galaxy mass may be an important independent factor associated with the origin of the gas, with the most massive fast-rotating galaxies in our sample always having kinematically aligned gas.

What drives the transition of galaxies from the disc dominated, star forming blue cloud to the elliptical dominated, quiescent red sequence? What role does the morphology, central supermassive black hole and galaxy environment play in this transition? I have attempted to answer these questions by using Bayesian statistics to infer a simple star formation history (SFH) describing the time, t_q, and exponential rate, τ, that quenching occurs in a galaxy. I use both the optical and NUV photometry of a galaxy in order to infer the posterior distribution of its SFH across the two dimensional [t_q, τ] parameter space. I then utilise the Galaxy Zoo 2 morphological classifications to obtain a morphology weighted, combined population distribution across each quenching parameter for a sample of galaxies. I apply this method across the blue cloud, green valley and red sequence of a sample of 126,316 galaxies and find a clear difference between the quenching timescales preferred by smooth and disc weighted populations, with three major routes through the green valley dominated by smooth (rapid rates, attributed to major mergers), intermediately classified (intermediate rates, attributed to galaxy interactions) and disc morphologies (slow rates, attributed to secular evolution). I hypothesise that morphological changes occur in systems which have undergone quenching with an exponential rate, τ < 1.5 Gyr, in order for the evolution of galaxies in the green valley to match the ratio of smooth to disc galaxies observed in the red sequence. I repeat this SFH analysis for a sample of 1,244 Type 2 AGN host galaxies and find statistical evidence for recent, rapid quenching, suggesting that this may be caused by AGN feedback. However I find that rapid quenching rates cannot account for all the quenching across the AGN host population; slow quenching rates, attributed to secular evolution, are also significant in the evolution of AGN host galaxies. I investigate this possible secular co-evolution of galaxies and black holes further by measuring the black hole masses of a sample of 101 bulgeless AGN host galaxies and compare them to typical black hole-galaxy scaling relations. I find that the measured black holes of the bulgeless galaxies are ~1-2 dex more massive than they should be, given their lack of bulges. This suggests that black hole-galaxy scaling relations may arise due to mutual correlations to the overall gravitational potential of the dark matter halo of the galaxy. I also considered the effect of the group environment on the time and rate that quenching occurs, with respect to the group-centric radius, for 4,629 satellite galaxies. I find that although mergers, mass quenching and morphological quenching are all occurring in groups, environmentally driven quenching mechanisms are also prevalent. However, I find that these environmentally driven quenching processes are not correlated with the velocity of a satellite within a group, ruling out ram pressure stripping as a possible mechanism. I discuss how all of these quenching mechanisms are likely to affect a galaxy across its lifetime, acting in concert to reduce the SFR, which in turn produces the wide distribution of quenching timescales seen across the colour-magnitude diagram. I discuss ideas for future work using the method employed in this work, including applying it to forthcoming data from large integral field unit surveys.

Thesis (doctoral)--Rijksuniversiteit Groningen, 1997. / Includes bibliographical references.

We present new measures of the rotation curves of disc galaxies from z~0.2 to z~1.7, using deep exposures from both DEIMOS and LRIS spectrographs on the Keck telescopes in combination with multi-band imaging from the Hubble Space Telescope. We do this with a new modelling code, curvation, which has been optimised to extract the rotation velocity measurements from galaxies at intermediate and high redshift. To this end, we conduct a bulge-to-disc de-composition to allow us to de-project observed velocities to extract a model of the intrinsic rotation curve. We demonstrate the improved accuracy and precision of these measurements via a number of tests, but primarily in recovering an intrinsic scatter of the high redshift Tully-Fisher relation which is similar to that found locally. We show for the first time that the stellar mass Tully-Fisher relation is tightly in place at z~1, the normalisation of which has evolved less than 0.02±0.02 dex in stellar mass from z~1.7 to z~0.2. We do however see evidence for evolution in classic B-band Tully-Fisher relation, which is brighter at z~1 by 0.85±0.28 magnitudes than that at z~0.3. This trend is consistent with what was previously known about the evolving star-formation rates of disc galaxies. We then explore the potential drivers of these trends in the Tully-Fisher relation by estimating the baryonic and dark matter content of our galaxies. We also discover a surprising trend in the bulgeless disc galaxies at high redshift, which may be evolving differently from other rotationally supported galaxies. In the context of work which has been conducted at z~2, we discuss our results of a stellar mass Tully-Fisher relation which is strikingly similar over two-thirds of the age of the Universe.