Zugl.: Tübingen, Univ., Diss., 2004. / Computerdatei im Fernzugriff.

Bonn, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Bonn, Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Zugl.: Tübingen, University, Diss., 2004.

University, Diss., 2003--Bonn.

The Edinburgh Multicolour Survey is a dataset of approximately 1.3 million images covering a contiguous area of 0.1 steradians at high Galactic latitudes. These data are derived from 130 UK Schmidt photographic plates taken in passbands U, B, V, R and I in two strips at declinations -5?and 0?, comprising the standard UKST fields 789-794 and 861-867 respectively. The aim of the survey is to produce a dataset containing accurate UBVRI information and morphological classification for every image detected in any waveband in the measured area, enabling the discrimination of intrinsically rare populations of objects with non-stellar colours from the foreground of normal Galactic stars. This thesis is concerned with (a) the development of the dataset from its initiation as raw plate material through to the production of the final five-band catalogues, and (b) the selection of quasars over a wide range in redshift. The plate material was scanned with the COSMOS fast-measuring machine at Ed?inburgh. Care was taken to reduce to a minimum the number of incorrectly measured images, which would badly contaminate candidate lists, and to minimise photomet?ric errors. The presence of two plates for each field/colour enables the rejection of spurious images which was performed after applying a local coordinate transformation between plates. Each set of UBVRI plates was taken close together in time to allow the correct measurement of the colours of variable stars and the rejection of images varying significantly in colour between epochs. Three different parameters were used to morphologically classify images over the full range in apparent magnitude. The data were calibrated with CCD sequences providing a total of about 30 measurements per UKST field, and zero-pointed using photoelectric measurements of bright (B = 15 ?16) stars. Systematic calibration errors outside the well-calibrated magnitude range and field-effects due to variations in image structure with position were minimised by new techniques such that the final photometric accuracy of the mean magnitude in each band is 0.02-0.05 magnitudes at about two magnitudes brighter than each plate-limit. The median depths of the final catalogues are U = 20.7, B = 20.8, V ? 19.6, R = 20.0 and I = 18.4. The survey, complete in all but fields 793 and 794, was used (i) to enable the selection of a new low-redshift sample of 69 quasars using a modification of the UVX technique which improves its efficiency, and (ii) as a basis for the selection of bright quasars at the highest redshifts z > 3.4. The UVX results compare very favourably with two similar samples, producing a corrected surface density of 0.40?0.05deg-2 for quasars with 15 < B < 18 and 0.3 < 2 < 2.2; examination of the distribution of objects in colour space provides further confirmation of the sample?s completeness. Power spectrum analysis and cor?relation function analysis produce some evidence for the presence of clustering in the3-D distribution on scale sizes up to r ~ 250 fi-1 Mpc; factors capable of producing such a signal spuriously are outlined and the implications of such a result discussed. For the highest redshift quasars, nearest-neighbour analysis was used to locate objects with non-stellar colours in multicolour space. The full range of survey colours increases sensitivity to z ? 4.1-4.5 as shown by two approaches: synthesizing quasar colours for a range of spectral type and redshift in a real dataset shows that the efficiency for most quasars with 3.4 < z < 4.5 is very high, and the inclusion of genuine quasars into a survey dataset confirms this conclusion. Three such quasars were confirmed spectroscopically with redshifts 2 = 3.4, 3.5 and 3.7 from a candidate list selected with 17 < R < 18.5, which imply a corrected surface density of 0.02-0.08 deg-2 for3.4 < z < 4.1. This is lower but not significantly different from estimates based on vi?sual emission-line surveys, and implies that the luminosity function for bright quasars has the same amplitude as that at z ~ 2. Various simple parameterisations for the evolution of the optical luminosity function are examined in the light of the new result.

The Gemini Near Infrared Spectrograph - Distant Quasar Survey (GNIRS-DQS) is the largest uniform, homogeneous survey of its kind, covering 260 quasars at 1.5 ≤ z ≤ 3.5. This unique survey, coupled with data from the Sloan Digital Sky Survey (SDSS), enables new investigations into redshifts, supermassive black hole masses (MBH), and accretion rates at high redshift through spectroscopic coverage of important rest-frame UV-optical emission lines. The importance of this survey is highlighted in the fact that the optical emission lines provide more reliable measurements of these quasar parameters than their UV counterpart. With such a unique sample compiled here, I construct prescriptions to calibrate these quasar parameters derived from rest-frame UV emission lines to those derived from rest-frame optical emission lines. These prescriptions provide important insight into how these parameters depend on redshift and are potentially biased as we look out further into the universe. Additionally, all the work completed with this sample will help shape our understanding of how these quasars and their host galaxies co-evolve over cosmic time.

In dieser Dissertation nutze ich den Gravitationslinseneffekt, um eine Reihe von kosmologischen Fragen zu untersuchen. Der Laufzeitunterschied des Gravitationslinsensystems HE1104-1805 wurde mit unterschiedlichen Methoden bestimmt. Zwischen den beiden Komponenten erhalte ich einen Unterschied von Delta_t(A-B) = -310 +-20 Tagen (2 sigma Konfidenzintervall).<br /> Außerdem nutze ich eine dreijährige Beobachtungskampagne, um den Doppelquasar Q0957+561 zu untersuchen. Die beobachteten Fluktuationen in den Differenzlichtkurven lassen sich durch Rauschen erklären, ein Mikrogravitationslinseneffekt wird zur Erklärung nicht benötigt. Am Vierfachquasar Q2237+0305 untersuchte ich den Mikrogravitationslinseneffekt anhand der Daten der GLITP-Kollaboration (Okt. 1999-Feb. 2000). Durch die Abwesenheit eines starken Mikrogravitationslinsensignals konnte ich eine obere Grenze von v=600 km/s f für die effektive Transversalgeschwindigkeit der Linsengalaxie bestimmen (unter der Annahme von Mikrolinsen mit 0.1 Sonnenmassen). <br /> Im zweiten Teil der Arbeit untersuchte ich die Verteilung der Dunklen Materie in Galaxienhaufen. Für den Galaxienhaufen Cl0024+1654 erhalte ich ein Masse-Leuchtkraft-Verhältnis von M/L = 200 M_sun/L_sun (innerhalb eines Radius von 3 Bogenminuten). Im Galaxienhaufen RBS380 finde ich eine relativ geringe Röntgenleuchtkraft von L =2*10^(44) erg/s, obwohl im optischen eine große Anzahl von Galaxien gefunden wurde. / In this thesis the gravitational lensing effect is used to explore a number of cosmological topics. We determine the time delay in the gravitationally lensed quasar system HE1104-1805 using different techniques. We obtain a time delay Delta_t(A-B) Delta_t(A-B) =-310 +- 20 days (2 sigma errors) between the two components. We also study the double quasar Q0957+561 during a three years monitoring campaign. The fluctuations we find in the difference light curves are completely consistent with noise and no microlensing is needed to explain these fluctuations. Microlensing is also studied in the quadruple quasar Q2237+0305 during the GLITP collaboration (Oct.1999-Feb.2000). We use the absence of a strong microlensing signal to obtain an upper limit of v=600 km/s for the effective transverse velocity of the lens galaxy (considering microlenses with 0.1 solar masses). The distribution of dark matter in galaxy clusters is also studied in the second part of the thesis. In the cluster of galaxies Cl0024+1654 we obtain a mass-to-light ratio of M/L = 200 M_sun/L_sun (within a radius of 3 arcminutes). In the galaxy cluster RBS380 we find a relatively low X-ray luminosity for a massive cluster of L =2*10^(44) erg/s, but a rich distribution of galaxies in the optical band.

Active galactic nuclei (AGN) ubiquitously show outflows. It is now widely recognized that these outflows are key components in the evolution of super-massive black holes and their host galaxies. As important as these outflows are, we still lack sufficient understanding of their structure and energetics. The majority of the work presented in this thesis involved photoionization modeling of AGN outflows along with analysis of density diagnostics in order to determine the distances and energetics of observed outflows. The main findings of these analyses are that 1) outflows are often at distances of hundreds to thousands of parsecs from the central supermassive black hole and 2) quasars outflows can be sufficiently powerful to provide feedback in galactic evolution scenarios. We also find in some cases that the recombination timescales of metal ions are long compared with the flux variability timescales. The large distances we find provide a challenge to current outflow models. For example, these outflows cannot be connected with an accretion disk surrounding the supermassive black hole as assumed in some models. Furthermore, the outflows may be out of equilibrium as we find in Mrk 509. In this case, a thorough understanding of time-dependent photoionization effects is necessary. In this thesis, I include early steps toward understanding time-dependent photoionization as well as ionization studies of accretion disk winds. The main results of these theoretical studies is that 1) the appearance of multiple ionization components in an outflow can be an artifact of the incorrect assumption that the outflow is in ionization equilibrium and 2) the shielding gas required in accretion-disk-wind models should have a clear signature in UV spectra, but none has been observed to date. / Ph. D.

The absorption lines found in the spectra of distant quasars provide a unique method of probing the physical conditions in the universe at early epochs. This thesis describes a study of the Lyman alpha forest absorption systems seen in the spectra of high redshift QSOs. The Anglo-Australian Telescope has been used to obtain high resolution spectra of several bright QSOs. Considerable effort has gone into developing statistical techniques for profile fitting to the data to objectively and reliably extract the parameters associated with each absorbing cloud. The distribution functions for these are given and discussed. Particular attention has been paid to the clustering properties of the Lyman alpha clouds and it is found that they are weakly (but significantly) clustered on small velocity scales. Possible interpretations of this result are discussed. One especially interesting aspect of QSO absorption systems concerns the potential for measuring, or obtaining limits on, the deuterium to hydrogen abundance at high redshifts. A knowledge of this quantity is important for constraining cosmological models and can also help us to understand the chemical evolution of light elements in galaxies. A series of numerical simulations has been carried out to explore the potential for such measurements and an absorption system has been analysed to obtain an upper limit to D/H at z = 3.