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 ~ 0.6 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.

Galaxy clusters are the most massive collapsed structures in the Universe and their properties offer a crucial insight into the formation of structure. High quality observational data is forthcoming with ongoing and upcoming surveys, but simulations are needed to provide robust theoretical predictions for comparison, as well mock data for testing observational techniques. Numerical simulations are now able to accurately model a range of astrophysical processes. This is highlighted in the BAHAMAS and MACSIS simulations, which have successfully reproduced the observed scaling relations of galaxy clusters. We use these simulations to quantify the impact baryons have on the mass distribution within galaxy clusters, as well as the bias in X-ray and weak lensing mass estimates. It is shown that baryons have only a minor affect on the spins, shape and density profiles of galaxy clusters and they have no significant impact on the bias in weak lensing mass estimates. When using spectroscopic temperatures and densities, the X-ray hydrostatic mass bias decreases as a function of mass, leading to a bias of ~40% for clusters with M_500 > 10^15 solar masses. In the penultimate chapter, we use the EAGLE and C-EAGLE simulations to construct more realistic mock cluster observations. The EAGLE simulations have been shown to successfully reproduce the properties of field galaxies and they are complemented by the C-EAGLE project, which extends this work to the cluster scale. We use these simulations to construct a cluster lightcone that accounts for the impact of uncorrelated large scale structure on cluster observables, including weak lensing mass estimates, the Sunyaev-Zel'dovich parameter and X-ray luminosity.

Today the search for and study of exoplanets is one of the most interesting areas of modern astronomy. Over the last two decades, the number of detected exoplanets continues to increase. At present, over 3,300 exoplanets have been discovered. This thesis presents high precision studies based on the transit and microlensing methods which are used to detect hot and cool exoplanets, respectively. In this thesis, the effects of intrinsic stellar noise to the detectability of an exomoon orbiting a transiting exoplanet are investigated using transit timing variation and transit duration variation. The effects of intrinsic stellar variation of an M-dwarf reduce the detectability correlation coefficient by 0.0-0.2 with 0.1 median reduction. The transit timing variation and transmission spectroscopy observations and analyses of a hot-Neptune, GJ3470b, from telescopes at Thai National Observatory, and the 0.6-metre PROMPT-8 telescope in Chile are presented, in order to investigate the possibility of a third body in the system and to study its atmosphere. From the transit timing variation analyses, the presence of a hot Jupiter with a period of less than 10 days or a planet with an orbital period between 2.5 and 4.0 days in GJ3470 system are excluded. From transmission spectroscopy analyses, combined optical and near-infrared transmission spectroscopy favour a H/He dominated haze (mean molecular weight 1.08 \pm 0.20) with methane in the atmosphere of GJ3470b. With the microlensing technique, real-time online simulations of microlensing properties based on the Besancon Galactic model, called Manchester-Besancon Microlensing Simulator (MaBulS), are presented. We also apply it to the recent MOA-II survey results. This analysis provides the best comparison of Galactic structure between a simulated Galactic model and microlensing observations. The best-fitting model between Besancon and MOA-II data provides a brown dwarf mass function slope of -0.4. The Besancon model provides only 50 per cent of the measured optical depth and event rate per star at low Galactic latitude around the inner bulge. However, the revised MOA-II data are consistent the Besancon model without any missing inner bulge population.

Esta tese apresenta resultados sobre a estrutura, relações de escala e cinemática para 48 galáxias em 22 grupos compactos de Hickson, sendo que a apresentação de mapas de velocidades, monocromáticos (na linha H alpha) e de dispersão de velocidades são feitos pela primeira vez para 35 galáxias em 12 dos grupos. A partir dos mapas de velocidades e imagens óticas, foi possível obter os parâmetros cinemáticos, morfológicos e as curvas de rotação das galáxias da presente amostra. Usando as velocidades máximas de rotação para cada galáxia (derivadas das curvas de rotação) e as luminosidades óticas, infravermelhas, as massas estelares e bariônicas, foram estudadas as diferentes relações de Tuly-Fisher (TF) para as galáxias dos grupos compactos. Comparando esses resultados com os apresentados por uma amostra de galáxias de campo, foi encontrado que as galáxias de grupos compactos seguem a relação de TF definida pelas galáxias em ambientes menos densos, no entanto algumas galáxias de baixa massa apresentam altas luminosidades para as suas velocidades de rotação. Surtos de formação estelar e atividade nuclear parecem ser os principais fatores que fazem com que as galáxias de baixas massas dos grupos compactos não estejam na relação de TF definida pelas galáxias do campo. Este resultado indica que as velocidades máximas de rotação não são alteradas em galáxias em interação e portato não há um stripping de massa significativo nas galáxias de grupos compactos, dentro de R(25). O uso das curvas de rotação para estudar a distribuição de massas nestas galáxias revelou que estas curvas apresentam um alto grau de assimetria, a qual seria produzida em eventos de interação galáxia-galáxia. Esses eventos, além de perturbar as curvas de rotação, conseguem expulsar parte do gás neutro das galáxias ao meio intra grupo. Usando dados ultravioleta, nesta tese foram encontradas vários sistemas estelares jovens no meio intergaláctico de grupos compactos. Esses sistemas podem se converter em galáxias satélites ou simplesmente serem dissolvidos, enriquecendo o meio intragrupo. / This thesis presents results on the kinematics, scaling relations and structures of 48 galaxies in 22 compact groups. For 35 galaxies in 12 compact groups, velocity fields, monochromatic maps (derived from H alpha observations) and velocity dispersion maps are presented for the first time. By using these data, it was possible to determine the kinematic and morphological parameters, the rotation curves and to derive the Tully-Fisher relation for the galaxies in dense environments. By using the maximum rotational velocity for each galaxy (derived from its rotation curve) and its optical and near-infrared luminosity and mass, the different Tully-Fisher relations for galaxies in compact groups were derived. Comparing these results with the results displayed by galaxies in less dense environments, it was found that galaxies in compact groups agrees with the Tully-Fisher relation defined by non-interacting galaxies. However, some of the low-mass galaxies are off the Tully-Fisher relation, having too high luminosities for their maximum rotational velocities. This scenario can be explained by a burst of star formation and/or by nuclear activity. We conclude that the maximum rotational velocities of compact groups galaxies are not affected during galaxy-galaxy interactions which implies that there is no significant mass stripping in galaxies of compact groups inside their optical radius. The mass distribution of galaxies in compact groups indicates that the rotation curves of these galaxies are highly asymmetric. The asymmetry could be produced by interactions between galaxies. These interactions, besides affecting the shape of the rotation curve, can eject some neutral gas from the disk of the interacting galaxies into the intragroup medium. By using ultraviolet data, we find several young star-forming regions in the intragroup medium of compact groups. It is still an open question wether these young stellar systems can survive and become new members of the group or if they will fall back onto their parent galaxies.

In this study we present GALEX UV, Sloan Digital Sky Survey, and Spitzer infrared imaging, along with an optical Hα map of the interacting galaxy pair Arp 107. IRAF photometry was used to analyze 29 star forming regions identified in previous work done with Spitzer colors. In this paper further analysis of the clumps of newly formed stars was done by creating Spectral Energy Distribution plots to sort the clumps as quiescent or starbursts. Color - color plots were used to estimate the ages and extinctions of the clumps by comparing magnitudes to stellar population synthesis models. Results seem to agree with previous models, and indicate a sequence of increasing age around the galaxy arm.

Les amas de galaxies sont des outils cosmologiques et astrophysiques essentiels, car ce sont les objets les plus grands et les plus massifs gravitationnellement liées dans l'Univers. L'étude de leur fonction de masse, de leur fonction de corrélation et des relations d'échelle entre leur masse et différentes observables nous permettent de tester les prévisions des modèles cosmologique et les scenarii de formation des structures. Ils sont aussi d'intéressants laboratoires pour l'étude de la formation et de l'évolution des galaxies, et de leur interactions avec le milieu qui les entourent, dans d’environnements denses. Pour y parvenir, estimer précisément leur masse revêt une importance fondamentale. J’ai étudié la précision de la richesse optique calculée par l’algorithme de détection d’amas RedGOLD (Licitra et al. 2016) en tant que mass proxy, en utilisant des mesures de lentilles gravitationnelles (weak lensing) et des observations en rayon X. J’ai mesuré les masses cumulées d’un échantillon de 1323 amas de galaxies dans le CFHTLS et NGVS à 0.2<z<0.5, dans l’intervalle de richesse 10-70. J'ai testé différents modèles prenant en compte les erreurs sur la position du centre de l'amas, les effets de lentille non faible (non-weak shear), le "two-halo term", la contribution de la galaxie centrale brillante et la dispersion intrinsèque de la relation masse-richesse. J'ai montré que la correction de la position du centre est nécessaire pour éviter un biais dans la mesure de la masse, alors que l'ajout de la galaxie centrale n'affecte pas les résultats. J'ai calculer les coefficients de la relation masse-richesse et ceux de la relation d'échelle entre masses issues du weak lensing et celle estimées à partir d'observations dans les rayons X. Mes résultats sont en accord avec les simulations et les précédents travaux publiés. / Galaxy clusters are essential cosmological and astrophysical tools, since they represent the largest and most massive gravitationally bound structures in the Universe. Through the study of their mass function, of their correlation function, and of the scaling relations between their mass and different observables, we can probe the predictions of cosmological models and structure formation scenarios. They are also interesting laboratories that allow us to study galaxy formation and evolution, and their interactions with the intra-cluster medium, in dense environments. For all of these goals, an accurate estimate of cluster masses is of fundamental importance. I studied the accuracy of the optical richness obtained by the RedGOLD cluster detection algorithm (Licitra et al. 2016) as a mass proxy, using weak lensing and X-ray mass measurements. I measured stacked weak lensing cluster masses for a sample of 1323 galaxy clusters in the CFHTLS W1 and in the NGVS at 0.2<z<0.5, in the optical richness range 10-70. I tested different weak lensing mass models that account for miscentering, non-weak shear, the two-halo term, the contribution of the Brightest Cluster Galaxy, and the intrinsic scatter in the mass-richness relation. I found that the miscentering correction is necessary to avoid a bias in the measured halo masses, while the inclusion of the BCG mass does not affect the results. I calculated the coefficients of the mass-richness relation, and of the scaling relations between the lensing mass and X-ray mass proxies. My results are consistent with simulations and previous works in the literature.

The goal of galaxy classification is to understand the physical basis for the wide range in shapes and structures exhibited by galaxies in the local and high redshift universe. We present a catalog of visually classified galaxies from the Sloan Digital Sky Survey with detailed morphological classifications including bars, rings, lenses, tails, warps, dustlanes, arm flocculence and multiplicity (so called ’fine structure’). This thesis explores the importance of galaxy morphology by probing its relationship to physical properties. Our analysis includes an investigation of correlations between fine structures and AGN activity. This sample defines a comprehensive local galaxy sample which we use to study the low redshift universe both qualitatively and quantitatively. We find the stellar mass appears to be a defining characteristic of a galaxy. The break in most correlations of physical properties with morphology is due to a lack of late type, massive disk galaxies. Our analysis of the size-mass relations of galaxies as a function of morphology (T-Type) has revealed many interesting connections. We find the size-mass relation of Sa, Sab, Sb, and Sbc galaxies bifurcates into two families of objects as one moves down the sequence such that the high concentration branch exhibits a similar slope to low concentration early type (E) galaxies suggesting a closer than expected physical (possibly evolutionary) connection between the two populations. We find bar fraction is bimodal with respect to mass (at 3 x 10^10 M) and color (at g - r ∼ 0.55). The dependence is seen to intimately depend on central concentration such that objects below the transition mass with low concentrations have a higher bar fraction than objects above the transition mass which have high bar fractions for high concentration systems. In addition we find the presence of an AGN alters the behavior and abundance of barred/ringed galaxies in the high mass peak such that the bar/ring fractions increase with mass in nonactive galaxies whereas they decrease with mass in active galaxies. AGN fractions are also decreasing in the same mass range possibly implying a positive correlation between fine structure and ring formation.

We conduct a deep mid-infrared census of nine massive galaxy clusters at (0 < z < 1.3) with a total of ~ 1500 spectroscopically confirmed member galaxies using Spitzer /IRAC photometry and established mid-infrared color selection techniques. Of the 949 cluster galaxies that are detected in at least three of the four IRAC channels at the >= 3 sigma level, we identify 12 that host mid-infrared selected active galactic nuclei (IR-AGN). To compare the IR-AGN across our redshift range, we define two complete samples of cluster galaxies: (1) optically-selected members with rest-frame VAB magnitude < -21.5 and (2) mid-IR selected members brighter than (M*_3.6 +0.5), i.e. essentially a stellar mass cut. In both samples, we measure f_IR-AGN ~ 1% with a strong upper limit of ~3% at z < 1. This uniformly low IR-AGN fraction at z < 1 is surprising given the fraction of 24 micrometer sources in the same galaxy clusters is observed to increase by about a factor of four from z ~ 0 to z ~ 1; this indicates that most of the detected 24 micrometer flux is due to star formation. Only in our single galaxy cluster at z = 1.24 is the IR-AGN fraction measurably higher at ~15% (all members; ~70% for late-types only). In agreement with recent studies, we find the cluster IR-AGN are predominantly hosted by late-type galaxies with blue optical colors, i.e. members with recent/ongoing star formation. The four brightest IR-AGN are also X-ray sources; these IR+X-ray AGN all lie outside the cluster core (R_proj > 0.5 Mpc) and are hosted by highly morphologically disturbed members. Although our sample is limited, our results suggest that f_IR-AGN in massive galaxy clusters is not strongly correlated with star formation at z < 1, and that IR-AGN have a more prominent role at z &gt; 1.

In this thesis we describe the generation and analysis of hydrodynamical simulations of galaxy clusters and their intracluster medium (ICM), using large cosmological boxes to generate large samples, in conjunction with individual cluster computations. The main focus is the exploration of the non-thermal processes in the ICM and the effect they have on the interpretation of observations used for cosmological constraints. We provide an introduction to the cosmological structure formation framework for our computations and an overview of the numerical simulations and observations of galaxy clusters. We explore the cluster magnetic field observables through radio relics, extended entities in the ICM characterized by their of diffuse radio emission. We show that statistical quantities such as radio relic luminosity functions and rotation measure power spectra are sensitive to magnetic field models. The spectral index of the radio relic emission provides information on structure formation shocks, {\it e.g.}, on their Mach number. We develop a coarse grained stochastic model of active galaxy nucleus (AGN) feedback in clusters and show the impact of such inhomogeneous feedback on the thermal pressure profile. We explore variations in the pressure profile as a function of cluster mass, redshift, and radius and provide a constrained fitting function for this profile. We measure the degree of the non-thermal pressure in the gas from internal cluster bulk motions and show it has an impact on the slope and scatter of the Sunyaev-Zel'dovich (SZ) scaling relation. We also find that the gross shape of the ICM, as characterized by scaled moment of inertia tensors, affects the SZ scaling relation. We demonstrate that the shape and the amplitude of the SZ angular power spectrum is sensitive to AGN feedback, and this affects the cosmological parameters determined from high resolution ACT and SPT cosmic microwave background data. We compare analytic, semi-analytic, and simulation-based methods for calculating the SZ power spectrum, and characterize their differences. All the methods must rely, one way or another, on high resolution large-scale hydrodynamical simulations with varying assumptions for modelling the gas of the sort presented here. We show how our results can be used to interpret the latest ACT and SPT power spectrum results. We provide an outlook for the future, describing follow-up work we are undertaking to further advance the theory of cluster science.

The goal of galaxy classification is to understand the physical basis for the wide range in shapes and structures exhibited by galaxies in the local and high redshift universe. We present a catalog of visually classified galaxies from the Sloan Digital Sky Survey with detailed morphological classifications including bars, rings, lenses, tails, warps, dustlanes, arm flocculence and multiplicity (so called ’fine structure’). This thesis explores the importance of galaxy morphology by probing its relationship to physical properties. Our analysis includes an investigation of correlations between fine structures and AGN activity. This sample defines a comprehensive local galaxy sample which we use to study the low redshift universe both qualitatively and quantitatively. We find the stellar mass appears to be a defining characteristic of a galaxy. The break in most correlations of physical properties with morphology is due to a lack of late type, massive disk galaxies. Our analysis of the size-mass relations of galaxies as a function of morphology (T-Type) has revealed many interesting connections. We find the size-mass relation of Sa, Sab, Sb, and Sbc galaxies bifurcates into two families of objects as one moves down the sequence such that the high concentration branch exhibits a similar slope to low concentration early type (E) galaxies suggesting a closer than expected physical (possibly evolutionary) connection between the two populations. We find bar fraction is bimodal with respect to mass (at 3 x 10^10 M) and color (at g - r ∼ 0.55). The dependence is seen to intimately depend on central concentration such that objects below the transition mass with low concentrations have a higher bar fraction than objects above the transition mass which have high bar fractions for high concentration systems. In addition we find the presence of an AGN alters the behavior and abundance of barred/ringed galaxies in the high mass peak such that the bar/ring fractions increase with mass in nonactive galaxies whereas they decrease with mass in active galaxies. AGN fractions are also decreasing in the same mass range possibly implying a positive correlation between fine structure and ring formation.