This thesis is in three parts: 1) a kinematical study of exoplanet host stars, 2) a study of the detached eclipsing binary V1094 Tau and 3) and observations of other eclipsing binaries. Part I investigates kinematical biases between two methods of detecting exoplanets; the ground based transit and radial velocity methods. Distances of the host stars from each method lie in almost non-overlapping groups. Samples of host stars from each group are selected. They are compared by means of matching comparison samples of stars not known to have exoplanets. The detection methods are found to introduce a negligible bias into the metallicities of the host stars but the ground based transit method introduces a median age bias of about -2 Gyr. Part II describes a detailed analysis of V1094 Tau. Spectra were analysed by the cross-correlation software TODCOR to obtain radial velocities, and uvby photometric light curves were analysed by the JKTEBOP software. Part III describes an observing run at SAAO Sutherland, aimed to survey detached eclipsing binaries. Light curves and two spectra each from two binaries were analysed, to determine masses and radii to the 10 to 30% level. This is a proof in principle that runs on 2-metre class telescopes can identify targets for detailed follow-up observations.

Simple single parameter models describing the evolution of globular cluster mass functions (GCMFs) are applied to early type Virgo galaxies. These models assume the dominant form of mass-loss in globular clusters (GCs) is two-body relaxation driven evaporation, and that the cluster initial mass function (CIMF) is described by a Schechter (1976) function. It is concluded that evaporation is primarily responsible for turning a Schechter (1976) CIMF into an evolved GCMF as observed in the Milky Way and other extant galaxies, and an estimate for the corresponding mass-loss rate is made. However, these models do not address the problem of why the GCMF is observed to be the same at all radii, and do not fully recover the shape of the GCMF in the most massive galaxies.

This thesis investigates the evolution of massive galaxies throughout the last 11 billion years using measured stellar masses and star formation rates. Firstly, we present a study of the resolved star-forming properties of a sample of distant massive (M > 10{11}) galaxies in the GOODS NICMOS Survey (GNS) within the redshift range 1.5 < z < 3 in order to measure the spatial location of ongoing star formation (SF). We find that the SFRs present in different regions of a galaxy reflect the already existent stellar mass density, i.e. high density regions have higher SFRs than lower density regions, on average. We find that these massive galaxies fall into three broad classifications of SF distributions. These different SF distributions increase the effective radii to z=0, by ~16 plus-minus 5 % , with little change in the Sersic index (n), with an average delta n = -0.9 plus-minus 0.9, after evolution. These results are not in agreement with the observed change in the effective radius and n between z ~2.5 and z ~0. We conclude that SF and stellar migration alone cannot account for the observed change in structural parameters for this galaxy population, implying that other mechanisms must additionally be at work to produce the evolution, such as merging. In Chapter 2, we present a study of the stellar mass growth of the progenitors of local massive galaxies at number densities of n < or = 1x10{-4} Mpc{-3} in the redshift range 0.3<z<3.0. We select the progenitors of massive galaxies using two number density selection techniques: a constant number density selection, and one which is adjusted to account for major mergers. We find that the direct progenitors of massive galaxies grow by a factor of four in total stellar mass over this redshift range. On average the stellar mass added via the processes of star formation, major, and minor mergers account for 23 plus-minus 8 %, 17 plus-minus 15 % and 35 plus-minus 14 %, respectively, of the total galaxy stellar mass at z=0.3. Therefore, 52 plus-minus 20% of the total stellar mass in massive galaxies at z=0.3 is created externally to local massive galaxies. We examine the dominance of these processes across this redshift range and find that at z>1.5 SF is the dominant form of stellar mass growth, while at z<1.5 mergers become the dominant form with minor mergers the dominant form of growth at z<1.0. We also explore the implication of these results on other galaxy formation processes such as the cold gas accretion rate of the progenitors of most massive galaxies over the same redshift range. We find that the gas accretion rate decreases with redshift with an average gas accretion rate of ~65 M yr{-1} over the redshift range of 1.5<z<3.0. Finally, we investigate the evolution of the properties of local massive galaxies over the redshift range 0.3<z<3.0. We again select the progenitors of local massive galaxies using a constant number density selection. We find that the average progenitor galaxy appears passive in $UVJ$ colours since at least z=3.0. We examine the UVJ colours and find that the average progenitor of a local massive galaxy has not lived on the blue cloud since z=3.0. The passive fraction of the progenitor population has increased from 56 plus-minus 7% at z=3.0 to 94 plus-minus 8% at z=0.3. This result implies that the majority of the progenitors of local massive galaxies have stopped actively star forming by z=3.0. Examining the structural properties of the progenitor galaxies we show that the size evolution of a galaxy sample selected this way is on average lower than the findings of other investigations into the size evolution of massive galaxies which have found that they must grow in size by a factor of 2-4 from redshift 3.0 to the present day. The average n of the progenitor population evolves significantly over the redshift range studied, with the population being dominated by low n objects (n<2.5) at z>1.7 and transitioning to high n objects at z<1.7. Splitting the high and low $n$ objects into SFing and passive samples. We find that 41 plus-minus 4 % of the sample at z>2.5 are passive low n systems, possibly implying that local massive galaxies were passive disk-like systems at early cosmic times.

The geometry of pulsar beams is one of the intrinsic properties of neutron stars, governing the pulse-profile phenomenon and other aspects of pulsar astron- omy. With a number of pulsars in our dataset, their beam geometry is derived from the polarisation position angle (PPA) using the simple polar cap emission and dipole field model. This includes the rotating vector model (RVM), for which the solutions can hardly be constrained or fail to be consistent because of the lim- itations of the model itself. The inconsistencies in the results suggest that the initial PPAs can be strongly perturbed by additional parameters above the emis- sion altitude, such as the plasma medium or rotational aberration effects, after which their characteristic shape is no longer related to the geometry via the RVM. We investigate further into the effects of wave propagation in the pulsar magne- tosphere, and find an indication that, in most cases, the RVM-calculated PPAs are likely to be altered by plasma effects.In recent years, there have been an increasing number of intermittent and mode-switching pulsars observed to have their radio pulse profiles correlated with the change in pulsar spin frequency (ν ̇) (e.g. Lorimer et al. 2012, Lyne et al. 2010). These two phenomena are understood to be related via the states of plasma in the magnetosphere. As one such pulsar, and also one with known geometry and other astonishing behaviour, PSR B1822–09 is studied in terms of the mode- switching properties, the hollow-cone model and the wave propagation in the magnetosphere. We also study the model for explaining the intermittent pulsars PSRs B1931+24, J1841+0500 and J1832+0029, and find it can be consistently applied for PSRs B1822–09 and B0943+10, and other profile-switching pulsars. However, aspects of the conclusions are limited because of the lack of understand- ing of the connection between the radio flux and the states of plasma. We are also able to use the difference in the PPAs between two states of PSR B0943+10 to predict the change in plasma states and ν ̇, which cannot be measured directly from timing analysis as its switching timescale is too short.

Measuring black hole spin has become a key topic in astrophysics, and recent focus on the spin powering of jets in X-ray binaries has heightened the need for accurate measurements of spin. However, the effects of spin are subtle, and are only imprinted on emission from very close to the black hole. This is revealed since the black hole spin defines the radius of the last stable orbit of the accretion disc, which is smaller for larger spin. Recent advances in X-ray observatories and spectroscopic techniques have enabled spin estimates for a number of black holes in X-ray binaries,but the accuracy of these methods, and the link between spin and jet power,have become very controversial subjects. In this thesis I address the former of these problems through X-ray reflection, which is one of two leading X-ray spectroscopic methods to measure black hole spin (the other being the ‘continuum’ method). Firstly, I investigate the systematic uncertainties associated with the X-ray reflection technique, and display how model degeneracies can severely affect the determination of spin. After establishing these potential flaws I then performed a systematic study of X-ray reflection during four hard state observations of the black hole GX 339−4, and show that the relativistic effects vary significantly over two orders of magnitude in luminosity. I show that this requires the accretion disc to be substantially truncated from the last stable orbit that is used to measure spin, thus rendering spin estimates impossible in the hard state. Following this I analyse over 500 archival observations of the same source with the Rossi Timing X-ray Explorer. Whilst these data cannot directly measure the inner disc radius, they allow a quantitative investigation of how X-ray reflection and the power-law co-evolve. Since the latter gives rise to the former, this allows changes in the accretion geometry to be revealed, which I show to be consistent with a truncated accretion disc in the hard state, and a gradual collapse of the corona in the soft state. Finally, I present three recent observations of GX 339−4 in the hard state with XMM-Newton, which allow an unprecedented simultaneous constraint on the inner accretion disc radius via the reflection and continuum methods. The two techniques agree, and present further compelling evidence for accretion disc truncation in the hard state.

This thesis concerns inferring core collapse supernova physics using gravitational waves. The mechanism through which the supernova is re-energised is not well understood and there are many theories of the physical processes behind the so called supernova mechanism. Gravitational waves provide an opportunity to see through to the core of a collapsing star. This thesis provides an algorithm that will analyse a detected gravitational waveform from a core collapse supernova and identify the supernova mechanism. This is achieved through the use of Bayesian model selection and a nested sampling algorithm. This Bayesian data analysis algorithm is called the Supernova Model Evidence Extractor (SMEE). SMEE is designed to classify detected gravitational waveforms from core-collapse supernovae and 3 different versions which employ different types of data have been developed. These 3 versions utilise time domain (which has been fast Fourier transformed into the frequency domain), power spectrum domain and spectrogram data and the success of each version is investigated. Firstly, results for a simplified idealised version of SMEE are discussed. In this scenario only a single gravitational wave detector is considered and the effect of the sky position of the source are ignored. Next, techniques which can be employed to improve SMEE are investigated. Finally, SMEE is tested using 3 gravitational wave detectors and the full effect of the time delay between detectors and the antenna response on each detector is included. As well as this, recoloured detector noise from the Science runs from both LIGO and Virgo are utilised here. This thesis demonstrates that each version of SMEE is successful and are able to infer the supernova mechanism for a galactic supernova. The spectrogram version of SMEE is deemed the most accurate and it is recommended that this technique should be further explored in the future.

This thesis focuses on the application of asteroseismology to red giants observed with Kepler alongside searching for solar g-modes using the Birmingham Solar Oscillations Network (BiSON). In the case of the Sun, solar gravity modes are highly sought after because they can shed light on the inner rotation profile of the Sun. This thesis contains work showing how the low frequency regime of BiSON data has been cleaned enabling the search to be made in BiSON data without instrumental artefacts. Moving onwards along the stars evolution, thanks to space mission such as Kepler and CoRoT tens of thousands of red giant stars have been observed allowing huge ensemble investigations. The ability to use high-quality, long datasets as constraints to shorter and noiser datasets has been investigated through fitting the background power of 6000 Kepler red giants. Red giants also offer the opportunity to study the inclination angle distribution of stars to confirm that the distribution conforms to the expected isotropy used in many simulations. This can be extended to inferring the obliquity through asteroseismology, as applied to a red-giant, M-dwarf eclipsing binary. This offering a means to probe obliquity distributions in in a different regime to that using traditional spectroscopic techniques.

Following the first detection of gravitational waves from a binary coalescence, the study of the formation and evolution of these gravitational-wave sources and the recovery and analysis of any detected event will be crucial for the newly realised field of observational gravitational wave astrophysics. This thesis covers a wide range of these topics including simulating the dense environments where compact binaries are likely to form, focusing on binaries containing an intermediate mass black hole (IMBH). It is shown that such binaries do form, are able to merge within a ∼ 100 Myr simulation, and that the careful treatment of the orbital evolution (including post-Newtonian effects) implemented here was crucial for correctly describing the binary evolution. The later part of the thesis covers the analysis of the gravitational waves emitted by such a binary, and shows it is possible to identify the IMBH with high confidence, together with most other parameters of the binary, despite the short-duration signals and assumed uncertainties in the available waveform models. Finally a method for rapid parameter estimation of gravitational wave sources is presented and shown to recover source parameters with comparable accuracy using only a small fraction ∼ 0.1% of the computational resources required by conventional methods.

It has been long known that galaxy properties are strongly connected to their environment; however, a complete picture is still missing. This work's aim is to better understand the role of environment in shaping the galaxy properties, using a sample of 25 redshift-selected galaxy groups at 0.060 < z < 0.063, for which 30 multi-wavelength parameters are available. Given the wide variety of group dynamical states, it was fundamental to try and identify different classes of groups performing a statistical clustering analysis using all the available parameters independently of their physical meaning, which resulted in two classes distinct by their mass. To move beyond mass driven correlations, a new clustering analysis was performed removing the mass dependent properties, this approach provided a categorisation in four classes with distinctive group properties. Based on this, the galaxy properties were investigated and the classes interpreted as follows: a class of field-like galaxies in the early stage of structure formation; a class of low-mass groups either still in formation phase, or evolved, but small because they are isolated; a class of massive groups with no, or very little, ongoing star formation, likely in a more evolved stage of structure formation; and a class of massive groups possibly experiencing merger events. The result obtained have shown that it is possible to distinguish between classes of groups and thus be able to study the property of galaxies in systems with homogeneous properties. The method developed applied to data sets with larger statistics and good data quality could be a powerful tool to study galaxy evolution in galaxy groups.

Inflation is the leading candidate to explain the initial conditions for the Universe we see today. It consists of an epoch of accelerated expansion, and regularly solves many problems with the Big Bang theory. Non-Gaussianity of the primordial curvature perturbation can potentially be used to discriminate between competing models and provide an understanding of the mechanism of inflation. Whilst inflation is believed to have lasted at least 50 - 60 e-folds, constraints from sources such as the cosmic microwave background (CMB) or large-scale structure of the Universe (LSS) only span the largest 6 - 10 e-folds inside today's Hubble horizon, limiting our ability to constrain the early universe. Strong constraints on the non-Gaussianity on smaller scales. Primordial black holes (PBHs) represent a unique probe to study the small-scale early Universe, placing an upper limit on the primordial power spectrum spanning around 40 e-folds smaller than those visible in the CMB. PBHs are also a viable dark matter candidate. In this thesis, the effect of non-Gaussianity upon the abundance of PBHs, and the implications of such an effect are considered. It is shown that even smaller non-Gaussianity parameters can have a large effect on the constraints that can be placed on the primordial curvature perturbation power spectrum - which can become stronger or weaker by an order of magnitude. The effects of super-horizon curvature perturbation modes at the time of PBH formation are considered, and it is shown that these have little effect on the formation of a PBH, but can have an indirect effect on the abundance of PBHs due to modal coupling to horizon-scale modes in the presence of non-Gaussianity. By taking into account the effect of modal coupling to CMB-scale modes, many models can be ruled out as a mechanism to produce enough PBHs to constitute dark matter.