The Department of Astronomy 2025-2026 Colloquium Series Presents:

Joseph’s Title: Tracing Black Hole Winds Across Cosmic Time with Broad Absorption Line Quasars

Abstract: Supermassive black holes (SMBHs) can launch powerful winds that inject large amounts of energy and mass into their host galaxies, potentially regulating galaxy evolution. One of the clearest observational signatures of these winds appears in broad absorption line (BAL) quasars, whose spectra show deep, blueshifted absorption features tracing gas traveling at tens of thousands of kilometers per second. Despite decades of study, the physical properties of BAL winds have remained poorly understood due to the complexity of their spectra. In this talk, I will present an overview of my research using BAL quasars to map the physical properties of SMBH winds, enabled by SimBAL, a spectral synthesis software that made possible the first systematic analysis of BAL quasar spectra and provided robust constraints on outflow properties for large samples of quasars. I will also discuss new discoveries of high-redshift BAL quasars from surveys such as DESI and future studies with JWST and 4MOST that will expand our understanding of SMBH outflows across cosmic time.


Cody’s Title: How Galactic Winds Influence Cosmic Ecosystems

Abstract: A central insight of modern galaxy formation is that galaxies are not isolated systems, but dynamic reservoirs of gas and stars that continuously exchange matter and energy with their surroundings. Galactic winds—driven by stellar and AGN feedback—can expel hundreds of solar masses of gas, dust, and metals to distances of tens of kiloparsecs, reshaping the structure and thermodynamics of the circumgalactic and intergalactic media. These winds regulate star formation, curb black hole growth, and may play a critical role in enabling the escape of ionizing radiation that reionized the Universe during the Epoch of Reionization. In this talk, I will discuss how the physical properties of galactic winds—including mass outflow rates—are inferred from spectral line diagnostics, the current state of the art in radiative transfer modeling and interpretation, and key systematic uncertainties that remain. I will then explore how winds influence the escape of ionizing photons by altering the multiphase structure of the interstellar medium. Finally, I will outline future directions for this work and describe how next-generation facilities such as the Extremely Large Telescopes will transform absorption line studies of galactic winds.