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"Quasar-mode feedback" occurs when momentum and energy from the environment of accreting supermassive black hole couple to the host galaxy. One mechanism for such a coupling is by high-velocity (up to ~0.2c) quasar-driven ionized outflows, appearing as blue-shifted absorption and emission lines in quasar spectra. Given enough energy and momentum, these outflows are capable of affecting the evolution of their host galaxies. This dissertation presents the studies of emission and absorption quasar outflows from different perspectives. (1). By conducting large broad absorption line (BAL) quasar surveys in both Sloan Digital Sky Survey and Very Large Telescopes (VLT), we determined various physics properties of quasar absorption outflows, e.g., the electron number density ((n_e), the distance of outflows to the central quasar (𝑅), and the kinetic energy carried by the outflow (𝐸̇_k). We demonstrated that half of the typical BAL outflows are situated at 𝑅 > 100 pc, i.e., having the potential to affect the host galaxies. (2). Our group carried out a Hubble Space Telescope program (PI: Arav) for studying the outflows in the Extreme-UV, collaborating with Dr. Gerard Kriss from Space Telescope Science Institute (STScI). We developed a novel method to fit the multitude of quasar absorption troughs efficiently and accurately. We have identified the most energetic quasar-driven outflows on record and discovered the largest acceleration and velocity-shift for a quasar absorption outflow. (3). By using the VLT data, Xu led the project to study the relationships between BAL outflows and emission line outflows. We found possible connections between these two types of quasar outflows, e.g., the luminosity of the [𝑂_III λ5007 emission profile decreases with increasing n_e derived from the BAL outflow in the same quasar. These findings are consistent with BAL and emission outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution. / Doctor of Philosophy / Super massive black holes (SMBHs) are believed to exist in the center of almost all massive galaxies, where the brightest accreting ones are named "quasars". "Quasar-mode feedback" occurs when momentum and energy from the environment of accreting SMBHs couple to the host galaxy. One mechanism for such a coupling is by high-velocity (up to ~0.2c) quasar-driven ionized outflows, appearing as blue-shifted absorption and emission lines in quasar spectra. Given enough energy and momentum, these outflows are capable of affecting the evolution of their host galaxies. Such quasar outflows are invoked to explain a variety of observations, e.g., the chemical enrichment of the intergalactic medium (IGM), the shape of the observed quasar luminosity function, and the self-regulation of the growth of the SMBHs. In this dissertation, I focus on studying the emission and absorption outflows observed in quasars spectra, collected with the largest telescopes and most powerful instruments in the world. (1). By conducting large broad absorption line (BAL) quasar surveys in both Sloan Digital Sky Survey and Very Large Telescopes (VLT), we determined various physics properties of quasar absorption outflows, e.g., the electron number density (n_e), the distance of outflows to the central quasar (𝑅), and the kinetic energy carried by the outflow (𝐸̇_k). We demonstrated that half of the typical BAL outflows are situated at 𝑅 > 100 pc, i.e., having the potential to affect the host galaxies. (2). Our group carried out a Hubble Space Telescope program (PI: Arav) for studying the outflows in the Extreme-UV, collaborating with Dr. Gerard Kriss from Space Telescope Science Institute (STScI). We developed a novel method to fit the multitude of quasar absorption troughs efficiently and accurately. We have identified the most energetic quasar-driven outflows on record and discovered the largest acceleration and velocity-shift for a quasar absorption outflow. (3). By using the VLT data, Xu led the project to study the relationships between BAL outflows and emission line outflows. We found possible connections between these two types of quasar outflows, e.g., the luminosity of the [𝑂_III] λ5007 emission profile decreases with increasing n_e derived from the BAL outflow in the same quasar. These findings are consistent with BAL and emission outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution.

Quasars can affect their surrounding environment through a process known as active galactic nucleus (AGN) feedback, through which the quasar can curtail the formation of stars, regulate the evolution of its host galaxy, and affect its surrounding environment in other ways. One possible mechanism for this process is a quasar's outflow, which can be observed as blueshifted absorption troughs in the quasar's spectrum. With enough kinetic power, an outflow can contribute to AGN feedback, regulating star formation and host galaxy evolution. By analyzing spectra from the Very Large Telescope (VLT) Ultraviolet Echelle Spectrograph (UVES) and the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS), we determined the physical parameters of the absorption outflows of five different quasars: including electron number density, Hydrogen column density, ionization parameter, distance from the source, and kinetic luminosity. We have found that an outflow's chemical abundance can be a determining factor of its ability to contribute to feedback effects. Particularly notable outflows include a mini broad absorption line (BAL) outflow system of SDSS J0242+0049, which we estimated to be ∼ 67 kpc away from the quasar, which is the farthest distance a mini-BAL has been found from its source. We also found a high velocity C IV BAL from the same quasar which showed noticeable signs of time variability, which suggests that the ionization of the outflow has changed over time. Another was SDSS J1321-0041 which displayed BAL troughs of C II and Si II, an unusual feature for an outflow of its type. In our analysis of the EUV500 BAL of QSO B0254-3327B, we compared it with other EUV500 outflows that have been previously studied, with a total sample of 24 outflows. In that comparison, we have found that the outflow of QSO B0254-3327B was one of the most ionized outflows in the sample. We have also found a weak negative correlation between logR and log |v|, where R is the distance of the outflow from its source, and v is the velocity of the outflow, with a Spearman rank of -0.43 and p value of 0.05, suggesting that the farther the outflow is from its source, the slower its velocity. / Doctor of Philosophy / From the prediction of their existence by general relativity, to the first direct image from the Event Horizon Telescope, black holes have been a fascinating subject for both physicists and the public alike. Most massive galaxies, including our own, are said to have a supermassive black hole (SMBH) at their center. In some galaxies, an accretion disk of orbiting matter forms around the black hole, in which gravitational energy is converted into light. This can sometimes cause the galactic nucleus to shine as bright as a star in the night sky, despite it being tens of thousands of times farther away from us than any star in our own galaxy. Such galactic nuclei are called "quasars", or "quasi-stellar objects". Some quasars show signs of outflowing gases which can absorb some of their emitted light. These are observed as blueshifted absorption troughs in quasar spectra from telescopes such as the Very Large Telescope (VLT) or the Hubble Space Telescope (HST). It is predicted that, with enough power, these outflows can contribute to a process called active galactic nucleus (AGN) feedback, through which the quasar can curtail the formation of stars, regulate the evolution of its host galaxy, and affect its surrounding environment in other ways. This dissertation discusses the study of five different quasars and their outflows observed with VLT and HST. We determined the physical parameters of the outflows such as electron number density, Hydrogen column density, ionization parameter, and distance of the outflow from its source, to ultimately find each outflow's kinetic luminosity, or kinetic power. While we found that some outflows are likely to be able to contribute to AGN feedback, there are a number of unknowns that still remain. Some interesting outflows we have found include the mini-BAL outflow of SDSS J0242+0049, which we found to be at a distance of ∼ 67 kpc (or ∼ 220, 000 lightyears) away from its source, the farthest distance observed to date. We also analyzed the extreme UV outflow of QSO B0254-3327B, which we compared to other outflows observed in a similar wavelength range. In that comparison, we found a weak negative correlation between velocity and outflow distance from the central source, suggesting that the farther away an outflow is from the quasar, the slower it becomes.

Cette thèse présente la mesure des redshifts photométriques et des paramètres physiques dans le cadre des sondages de galaxies à grande échelle, ainsi que la contrainte qui peut en être extraite sur l'évolution des galaxies. Je montre notamment dans cette thèse dans quelle mesure la calibration photométrique affecte la précision des redshifts photométriques, afin de contraindre la stratégie photométrique à développer pour la mission Euclid.Afin de prendre en compte les problèmes inhérents à l'observation, les analyses ont été effectuée sur la base de données observées dont la configuration est proche de celle qui est attendue pour Euclid. Ces données combinent de nouvelles observations en proche-infrarouges conduites pour couvrir le sondage spectroscopique VIPERS et la photométrie du CFHTLS. Sur la base des conclusions tirées de cette analyse, j'ai produit le nouveau catalogue photométrique de VIPERS, ainsi que le catalogue de redshifts photométriques associé. J'ai finalement utilisée la même photométrie pour dériver les paramètres physiques d'environ 760 000 galaxies, réparties sur plus de 22 degrés carrés à une magnitude limite Ks(AB) < 22. J'ai ainsi pu étudier l'évolution de la fonction de masse stellaire entre les redshifts z = 0.2 et z = 1.5. Ceci a permis de montrer que les galaxies dont la masse stellaire est d'environ log(M/Msol) = 10.66 voient généralement leur formation stellaire stoppée en 2 à 4 milliards d'années, alors que les galaxies de faible masse (log(M/Msol) < 9.5) ne formant plus d'étoiles ont vu leur formation stellaire être arrêtée 5 à 10 fois plus rapidement (en environ 0.4 milliard d'années). / This thesis presents the measurement of the photometric redshifts and physical parameters in the framework of large scale surveys, and their constraint on galaxy evolution. The photometric redshift measurement allows us to study the entire photometric sample. For this reason, the weak lensing signal measurement used in the Euclid mission as a primary cosmological probe will rely on photometric redshift measurements. However, the method is strongly affected by the quality of the photometry. In particular, I show in this thesis how the photometric calibration impacts the photometric redshift precison, in order to constrain the photometric strategy to use in the Euclid mission.Aiming to take into account for observationnal problems, the analysis is done with observationnal data whose photometric configuration is close to the expected Euclid one. These data combine new near-infrared observations conduected to cover the VIPERS spectroscopic survey and the CFHTLS photometry.Using the conclusions of this analysis, I have producted the new photometric catalogue for VIPERS and the associated photometric redshift calalogue.Finally, I used the same photometry to compute the stellar masses of 760,000 galaxies covering 22 square degrees at the limiting magnitude Ks(AB) < 22. This enabled me to study the evolution of the stellar mass function between redshifts z= 0.2 and z = 1.5. We have then shown that the star formation of galaxies with stellar masses around log(M/Msol) = 10.66 is stopped in 2-4 Gyr, while in quiescent low-mass (log(M/Msol) < 9.5) galaxies, the star formation has been stopped 5-10 times faster (approximatelly in 0.4 Gyr).

Les modèles semi-analytiques (SAMs) constituent aujourd'hui le meilleur outils d'analyse et d'étude pour la formation et l'évolution des galaxies individuels mais également des regroupements de galaxies appelés amas. Alors qu'ils reproduisent avec succès les fonctions de masse stellaire, de corrélation à deux points, de luminosité des galaxies locales (z=0), ils échouent dans les prédictions des propriétés des galaxies plus jeunes, à plus haut décalage vers le rouge. Et ce d'autant plus que la masse stellaire est faible. Ces inconsistances entre les modèles et les observations démontrent que l'histoire de l'assemblage des ces galaxies, en relation avec l'accrétion de gaz, la formation stellaire et leurs halos de matière noire n'est pas bien comprise. Dans cette thèse, nous introduisons une nouvelle version du modèle semi-analytique GalICS et nous l'utilisons pour explorer l'impact, sur la formation stellaire des galaxies à faible masse, de la rétroaction des supernovae et des trous noirs supermassifs ainsi que des processus de photo-ionisation. Ces deux mécanismes sont communément utilisés pour réduire la formation de nouvelles étoiles dans les galaxies peu massives. Nous montrons que, même appliqué avec de très fortes efficacités, ces deux processus ne peuvent pas expliquer simultanément les fonctions de masse, de luminosité et la relation entre masse stellaire et masse des halos de matière noire pour les galaxies évoluant à grand décalage spectral. Suite à ce constat, nous introduisons deux recettes ad-hoc pour la formation stellaire. Dans un premier temps nous appliquons une forte modification de l'efficacité de formation stellaire en relation directe avec la masse de matière noire de leur halo hôte. Cette première approche conduit à de bons résultats, en particulier dans le régime des faibles masses stellaires mais il présente, par construction un profond désaccord avec la loi de formation stellaire observées par Kennicutt. Pour cela, nous introduisons une seconde modification, plus profonde, basée sur l'existence d'une composante de gaz, évoluant en périphérie des premiers disques galactiques, mais ne pouvant pas, pour des raisons encore mal comprises, former de nouvelles générations d'étoiles. Progressivement, ce gaz impropre à la formation stellaire est convertit, il alimente alors la formation d'étoile. L'introduction de ce nouveau réservoir, introduit un délai entre le moment ou le gaz s'effondre au centre du halo et le moment ou ce gaz. Ce nouveau modèle donne de très bons résultats mais il pose la question de l'origine de ce gaz impropre à la formation stellaire. Nous abordons dans cette thèse quelques piste de recherche dans le cadre de la formation des grandes structures peuplant notre Univers. / Semi-analytical models (SAMs) are currently the best way to understand the formation of galaxies and clusters within the cosmic web dark-matter structures. While they fairly well reproduce the local stellar mass function, correlation function and luminosity function, they fail to match observations at high redshift (z>3) in most cases, particularly in the low-mass range. The inconsistency between models and observations indicates that the history of gas accretion in galaxies, within their host dark-matter halo, and the transformation of gas into stars, is not well followed. In this thesis, we introduce a new version of the GalICS model and we use it to explore the impact, on the star formation and in the low-mass range, of supernovae feedback and photo-ionization. These two mechanisms are commonly used to limit the amount of gas available to form stars.We will show that, even with a strong efficiency, these two process cannot explain the observed stellar mass function, luminosity functions, and the stellar mass versus dark matter halo mass relation. We will thus introduce two ad-hoc modifications of the standard paradigm. We propose first a strong modification of the star formation efficiency as a function of the dark matter halo mass. This model produces good results, especially on the faint end of the stellar mass function, but is, by construction, in disagreement with the well known Kennicutt star formation law. We will thus introduce a deeper change, based on a no star-forming gas component, and a new gas distribution in the galaxy discs. The reservoir in which stays the no star-forming gas generates a delay between the gas accretion and star formation. This model is in very good agreement with a large set of observations. However, it poses the question of the origin of the no star-forming gas. We will discuss its origin in the framework of the large scale disturbed dynamic of high-redshift structures.

Galaxy evolution depends on a diverse suite of factors, from the environment in which the galaxy exists to the number of supernovae that explode throughout its history. The structure and stellar populations present will also be altered by a galaxy's merger history, stellar mass, star formation rate, among other influences. Some factors, like mergers, are dependent on the environment of the galaxy, while others, like feedback from star formation, are intrinsic to the galaxy themselves. Dwarf galaxies are sensitive to many of these factors due to their smaller masses, hence shallower potential wells. Dwarfs are also interesting in themselves as the least massive structures that can form stars, forming the faint limit of galaxy types. There is some indication that the evolutionary pathway of dwarfs might be different than their more massive counterparts. Indeed, some dwarfs may be the stripped remnants of larger galaxy after a major interaction. Regardless, dwarfs are thought to be the building blocks of larger galaxies via hierarchical galaxy formation and understanding these small dwarfs helps us build a more complete picture of galaxy formation and evolution at all masses. As dwarfs generally have low stellar mass, they are very faint. Our most complete sample of dwarfs is therefore restricted to those that are nearby. These nearby systems are dominated by dwarfs satellite to the Milky Way and M31. However, the evolution of these satellites will be greatly influenced by their massive host. By studying nearby isolated dwarfs, we can try to separate the secular evolutionary processes of dwarfs from the influence of their larger host. Additionally, stellar populations can be resolved in these nearby galaxies, and so their structures can be probed to much fainter regimes than integrated light studies allow. The Sagittarius Dwarf Irregular Galaxy (Sag DIG) is one of the most isolated, low mass galaxies, located at the edge of the Local Group. Its isolation from other galaxies coupled with its relative proximity provide an excellent opportunity to study the intrinsic properties of this low mass system. We preform an in-depth analysis of its resolved stellar populations and its structural properties as the first galaxy in the larger dataset, Solitary Local Dwarfs Survey (Solo). Solo is a wide field photometric study targeting every isolated dwarf galaxy within 3 Mpc of the Milky Way. Solo is based on (u)gi multi-band imaging from CFHT/MegaCam for northern targets, and Magellan/Megacam for southern targets. All galaxies fainter than M ~ -18 (in the V band) situated beyond the nominal virial radius of the Milky Way and M31 (> 300 kpc) are included in this volume-limited sample, for a total of 42 targets. For Sag DIG, we provide updated estimates of its central surface brightness and integrated luminosity, and trace its surface brightness profile to a level fainter than 30 mag./sq.arcsec. Sag DIG is well described by a highly elliptical (disk-like) system following a single component Sersic model. However, a low-level distortion is present at the outer edges of the galaxy that, were Sag DIG not so isolated, would likely be attributed to some kind of previous tidal interaction. Further, we find evidence of an extremely low level, extended distribution of stars beyond ~5 arcmins (> 1.5 kpc) that suggests Sag DIG may be embedded in a very low density stellar halo. We compare the stellar and HI structures of Sag DIG, and discuss results for this galaxy in relation to other isolated, dwarf irregular galaxies in the Local Group. Sag DIG, and the similarly isolated dwarf Aquarius, both have HI distributions that are more circular than their stellar components. In contrast, Wolf - Lundmark - Mellote (WLM), another isolated but slightly more massive dwarf, has stellar and HI components that trace each other well. Sag DIG and Aquarius also differ in that there is no signature of rotation in the HI of Sag DIG, while there is clear rotation in both the HI and stellar component for Aquarius. These preliminary comparisons demonstrate some of the potential analysis which will be possible on a much larger scale with the full Solo Survey. / Graduate / 0606 / higgs@uvic.ca

In this thesis I investigate the dynamics and stellar populations of a sample of 28 edge-on early-type (S0--Sb) disk galaxies, 22 of which host a boxy or peanut-shaped bulge. I begin by constructing mass models of the galaxies based on their observed photometry and stellar kinematics. Subject to cosmologically motivated assumptions about the shape of dark haloes, I measure in a purely dynamical way their stellar and dark masses. I make a preliminary comparison between the dynamically determined stellar masses and those predicted by stellar population models. I then compare the Tully-Fisher (luminosity--velocity) relations of the spirals and S0s in the sample. I show that S0s are systematically fainter at a given rotational velocity, but the amount by which they are fainter is less than expected by models in which they are the products of truncation of star formation in spirals. This raises the possibility that S0s are smaller or more concentrated than spirals of the same mass. I then study the vertical structure of the boxy and peanut-shaped bulges of a subset of the sample. Among this sample of five galaxies, I find one example in which the stellar populations show no evidence that the bulge and the disk formed in different processes, and in which the bulge is in perfectly cylindrical rotation, i.e. its line-of-sight velocity does not change with height above the disk. This galaxy is probably a pure disk galaxy. However, even with this small sample, I also show that cylindrical rotation and homogeneous stellar populations are not ubiquitous properties of boxy and peanut-shaped bulges. Finally I analyse central and radial trends in the stellar populations of the bulges of full sample of 28 galaxies. I find that, at a given velocity dispersion, the central stellar populations of these barred early-type disk galaxies are identical to those of elliptical galaxies, which suggests that secular evolution does not dominate the centre of these galaxies. However, the radial metallicity gradients are shallower than those of ellipticals. This is qualitatively consistent with chemodynamical models of bar formation, in which radial inflow and outflow smears out pre-existing gradients.