This thesis clarifies the role of disk components embedded in the spheroids of early type galaxies, with particular focus on the frequency and structure of disks in galaxies conventionally classified as "ellipticals". We discuss both photometric and spectroscopic means of assessing disks. Using simple photometric models, we explore what physical disk parameters result in detectable photometric signatures. We discuss in particular the deviations of the projected isophotes from perfect ellipses in disk/spheroid systems. We show that a wide range of intrinsic disk-to-spheroid ratios (D/S) can produce very similar photometric signatures, depending on viewing angle. We find the distribution of observed isophote distortions in a sample of ellipticals with published surface photometry to be consistent with the D/S hypothesis, implying that about half of the sample members could contain disks with D/S ∼ 0.25. To confront our models with a more suitable set of data, we obtained surface photometry at 0.4μ and 1.6μ for a statistical sample of about 80 galaxies, comprised of both E's and S0's. Analyzing this data set we find that in any given luminosity bin of early type galaxies, one third of the objects contain disks whose detectability depends on a favourably high inclination. This fraction was estimated independently from isophote distortions and from radial luminosity profiles. The apparent smooth transition between disk galaxies and purely spheroidal objects can be explained exclusively by changes in the viewing angle, even assuming two discrete classes of early type galaxies (either having substantial disks or none at all). There is no need to invoke continuity along the Hubble sequence from E's to S0's. For the members of this sample we find a considerable range in D/S, 0.15 < D/S < 5. However, most of that variation is caused by changes in the relative scale lengths rather than by changes in disk surface brightness. To analyze kinematic signatures of disk components we develop an optimal algorithm to extract the line-of-sight velocity distribution (LOSVD) from the broadening of absorption line spectra. Analyzing the LOSVD's in two kinematically distinct cores of elliptical galaxies, we find that they can be modelled dynamically as small disks embedded in the large spheroid. The range in rotational support, 1.3 < ν/σ < 4, of these disks suggests that some of them have formed dissipatively and others through a merger event.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references. / Also available by subscription via World Wide Web / xvii, 281 leaves, bound ill., charts 29 cm

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references.

Thesis (Ph.D) - Swinburne University of Technology, Faculty of Information & Communication Technologies, 2007. / A thesis presented in fulfillment of the requirements of Doctor of Philosophy, Faculty of Information and Communication Technologies, Swinburne University of Technology, 2007. Typescript. Bibliography p. 109-118.

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In studies of triaxial elliptical galaxies, one of the least observationally studied phenomena is figure rotation. Figure rotation has important consequences for the orbital structure and could explain the survival of steep nuclear cusps. For this project, we thus wish to investigate the possibility of measuring the figure rotation of an elliptical galaxy for which the geometry is approximately known using the Tremaine-Weinberg (TW) method. Originally meant for measuring the pattern speed of barred disk galaxies, we test the validity of the method using NGC 5266, a minor-axis dust-lane elliptical. In the process, the galaxy's line-of-sight velocity distribution (LOSVD) is measured along several slit positions. Measurements of the velocity v, velocity dispersion a, skewness /J3, and kurtosis h^ are derived using the Fourier Correlation Quotient method and a Gauss-Hermite series. This work represents the most detailed stellar kinematic measurements of NGC 5266 to date and confirm that it is one of the fastest rotating elliptical galaxies known today (Varnas et al. 1987). We find a maximum velocity of about 167 km s_1 at both a PA of 274° and 304°. This is compared to a maximum of 212 ± 7kms~1 at a PA of 287° found elsewhere (Varnas et al. 1987). The TW method yields significantly different values for the pattern speed. These vary between -19 and 22kms Wcsec"1. The discrepancy between the results casts doubt on the ability to straightforwardly apply the TW method to elliptical systems, but the study provides some insight into how the method may be more successfully implemented in the future. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Thesis (Ph.D.)--McMaster University (Canada), 1996. / Source: Dissertation Abstracts International, Volume: 58-06, Section: B, page: 3088. Adviser: W. E. Harris.

This thesis presents deep photometry of the globular cluster system of the massive elliptical galaxy, M49. Using the C and T1 Washington filters from the MOSAIC camera on the Cerro Tololo Inter-American Observatory 4m telescope, we studied the color, metallicity and luminosity distributions of the globular cluster system. We find a strong bimodality in the color and metallicity distributions of the globular cluster system down to a magnitude of R <24, with 1718 clusters belonging to the blue population and 698 to the red population. In agreement with previous studies, the blue sequence does not exhibit a strong mass-metallicity relation. No difference is found in the mass-metallicity relation between the inner and outer clusters of M49. These results suggest that the mechanism responsible for the mass-metallicity re- lation is not local and may be affected by the galaxy’s individual dynamic history, location in the galaxy cluster and the formation of the globular cluster system itself. We suggest a mechanism based on accretion of gas by proto-clusters as they orbit within their parent dwarf galaxies. The latter would fit the observed behavior of the MMR. / Thesis / Master of Science (MSc)

Lenticular and elliptical galaxies, collectively referred to as "early-type galaxies" (ETGs), are commonly thought to represent the end-points of galaxy evolution. Lying in the red sequence of galaxies, these objects are defined by their mostly old stellar populations and by their "red and dead" appearance in optical observations. Much progress in understanding these objects has been made with integral-field spectroscopy in recent years, with results repeatedly pointing to a link between early-type galaxies and high-redshift spiral galaxies. However, the exact nature of this link remains unclear, with a wide variety of evolution scenarios likely required to fully explain the range of observed early-type galaxy properties. In my study, I analysed observations of twelve early-type galaxies taken with the Mitchell Integral-Field Spectrograph at McDonald Observatory, Texas. These galaxies have previously been found to contain detectable quantities of neutral hydrogen gas, with ten out of the twelve displaying large-scale hydrogen disks. I extracted line-of-sight kinematics of the stellar and ionised gas components of these galaxies, and I used various modelling approaches to constrain their stellar population parameters as well as their three-dimensional mass structure in terms of both dark and visible components. An important feature of this study is the wide field of view of the spectroscopic observations, which reach beyond two half-light radii for almost all of the sample; this remains rare for integral-field unit (IFU) studies of ETGs, and so sets this study apart from most earlier works. The gas-rich nature of the sample is likewise novel. I find all aspects of my analysis to yield a consistent view of these galaxies' evolution, in which one or more gaseous interaction events served to shape them into their observed forms. I find these galaxies to contain low dark matter fractions on average within the inner half-light radius, and I also find mass modelling to favour near-isothermal total density profiles over much of the sample.