Quasar outflows are a major candidate for Active Galactic Nuclei (AGN) feedback, and their capacity to influence the evolution of their host galaxy depends on the mass-flow rate (M) and kinetic luminosity (E) of the outflowing material. Both quantities require measurement of the distance (R) to the outflow from the central source as well as physical conditions of the outflow, which can be determined using spectral observations of the quasar. This thesis presents spectral analyses leading to measurements of R, M and E for three different quasar outflows. Analysis of LBQS J1206+1052 revealed multiple diagnostic spectral features that could each be used to independently determine R. These diagnostics yielded measurements that were in close agreement, resulting in a robust outflow distance of 840 pc from the central source. This measurement is much larger than predicted from radiative acceleration models (~0.01-0.1 pc), suggesting that outflows appear much farther from the central source than is generally assumed. The outflow in SDSS J0831+0354 was found to carry a kinetic luminosity of 10^45.7 erg/s, which corresponds to 5.2 per cent of the Eddington luminosity of the quasar. This outflow is one of the most energetic outflows to date and satisfies the criteria required to produce AGN feedback effects. A variability study of NGC 5548 revealed an obscuring cloud of gas that shielded the outflow components, dramatically lowering their ionization state. This resulted in the appearance of absorption from the rare element Phosphorus, as well as from sparsely-populated energy levels of CIII and SiIII. These spectral features allowed for an accurate determination of R and for constraints on the ionization phase to be obtained. The latter constraints were used to develop a self-consistent model that explained the variability of all six outflow components during five observing epochs spanning 16 years. / Ph. D.

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.

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