"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.