Astrophysics and Astronomy Commons^™

Electromagnetic Counterparts To Active Galactic Nucleus Disk-Embedded Binary Black Hole Mergers, Emily Mcpike

Dissertations, Theses, and Capstone Projects

The accretion disks of active galactic nuclei (AGN) are promising environments for producing binary black hole (BBH) mergers, which have been detected via gravitational waves (GW) with LIGO-Virgo-KAGRA (LVK). BBH mergers embedded in AGN disks are unique among GW formation channels in their generic ability to produce electromagnetic (EM) counterparts, via interactions between the merger remnant and the surrounding disk gas (though these are not always observable). While such mergers represent valuable multi-messenger sources, the lack of predictive statistical models in existing literature currently limits our ability to select possible EM counterparts with GW detections in archival data and in …

Considering Numerical Relativity For Upgrades In Mcfacts Merger Dynamics, Shawn K. Ray

Dissertations, Theses, and Capstone Projects

Binary black hole mergers (BBH), some likely originating from active galactic nuclei (AGN), are observed by ground-based detectors such as LIGO-Virgo-KAGRA (LVK) and will be detected by future space-based detectors such as the Laser Interferometer Space Antenna (LISA) and the Laser Interferometer Lunar Antenna (LILA). The dynamics of AGN may be responsible for a significant fraction of BBH mergers soon to be observed by LISA and LILA, yet the dynamics of BBH mergers within AGN disks remains ambiguous despite their appearance in gravitational wave observations. Monte carlo For AGN Channel Testing and Simulation (McFACTS) is an open-source software used to …

Inductive Biases In Field-Level Cosmological Inference From Galaxy Catalogs, James O'Connor Baldwin

Dissertations, Theses, and Capstone Projects

We perform field-level likelihood-free inference of the matter density parameter Ωm from simulated galaxy catalogs using machine learning models with differing inductive biases. Using features extracted from hydrodynamic simulations in the CAMELS suite, we investigate how both observable choice and model architecture govern the extraction of cosmological information. We consider galaxy positions and line-of-sight peculiar velocities, both separately and in combination, and compare permutation-invariant Deep Sets, implemented with either standard multilayer perceptrons (MLPs) or Kolmogorov–Arnold Networks (KANs), to graph neural networks (GNNs) implemented with MLPs, which explicitly encode spatial relations. We evaluate inference performance under both in-distribution and out-of-distribution (OOD) …

Discovery Of Newly Resolved Filament And Extraplanar Gas In M33 With The Local Group L-Band Survey, Emma Taylor Kleiner

Dissertations, Theses, and Capstone Projects

The proximity of the Local Group allows for unparalleled resolution of the structure and kinematics of the ISM while simultaneously observing the overall rotation of the galaxy. These nearby galaxies present the opportunity to probe stellar feedback processes in various galactic environments. M33 in particular, offers insight into the nature of the extended neutral gas and its relationship with the star-forming disk and the surrounding CGM, by way of its classic star-forming spiral and relatively undisturbed system. Outside of M33’s distinguished warp, the galaxy offers little evidence of satellites and shows few signs of interaction, begging the question of how …

1d Crust-Magnetosphere Coupling Model For Magnetars, Kennedy M. Jeter

Dissertations, Theses, and Capstone Projects

Magnetars are the most extremely magnetized objects in the universe. Their strong magnetic fields generate high-energy magnetic flares with instantaneous luminosity that can outshine their host galaxy. Previous works have explored how Hall drift in the crust affects the dynamics of magnetic field lines in the magnetosphere. This work investigates how a change in the magnetosphere, such as a flare or an outburst, can excite Hall evolution in the crust. We investigate how the twisting and untwisting of magnetic field lines in a magnetar’s magnetosphere launches Hall waves through its crust using a one-dimensional numerical model. We use the Dedalus …

Identifying Helium Emission-Line Stars With The Condor Array Telescope, Julia Stewart

Dissertations, Theses, and Capstone Projects

Helium emission-line stars, including cataclysmic variables (CVs), AM Canum Venaticorum (AM CVn) binaries, symbiotic stars, and X-ray binaries, are tracers of compact object binary populations in the Milky Way, and may be viable progenitor systems of Type Ia supernovae. Their space densities are not well constrained - just over 100 AM CVn stars are known out of a Galactic population that may be closer to 100,000. Identifying such systems in large numbers requires wide-field, narrow-band photometric surveys capable of detecting faint emission-line sources across significant sky areas.

In this thesis, I present a narrow-band photometric search for helium emission-line stars …

The Space In Between, Cailyn Dawson

Theses and Dissertations

This paper asks the question: is it possible for our bodies to hold contradicting identities at the same time?  Through monochromatic self- portraits, the artist creates a link between quantum mechanics and painting, using the principle of superposition to depict these multiple unformed states of being.

Searching Within Galaxies For The Earliest Signs Of Quenching With Spatially Resolved Star Formation Histories In Uvcandels Galaxies At Z < 0.3, Charlotte Olsen, Eric Gawiser, Charlotte Welker, Harry Teplitz, Kartheik Iyer, Xin Wang, Marc Rafelski, Rogier A. Windhorst, Anton Koekemoer, Anahita Alavi, Ben Sunnquist, Norman Grogin, Yicheng Guo, Christopher J. Conselice, L. Y. Aaron Yung, Kalina Nedkova, Bahram Mobasher, Ray A. Lucas, Vihang Mehta, Y. Sophia Dai, Jonathan P. Gardner

Publications and Research

Understanding the complicated processes that regulate star formation and cause a galaxy to become quiescent is key to our comprehension of galaxy evolution. We used eight well-resolved star-forming z < 0.3 galaxies from the UVCANDELS survey, where a total of 10 Hubble Space Telescope bands, including UV follow-up in UVIS/F275W, allow us to reconstruct the star formation histories (SFHs) of regions across each galaxy. This approach provides a powerful tool to explore the spatiotemporal connection between star formation and galaxy evolution. The spatial and temporal profiles of stellar mass and star formation rate (SFR) surface density were obtained from the SFHs of these regions. We measure scaling relations and projected radial profiles of regions within each galaxy at the time of observation and at 1 Gyr lookback time, noting possible trends in the evolution. By comparing the change in star formation over time, we can infer the timing and location of star formation and see early signs of star formation shutting off before quenching occurs. We compared the SFR density–stellar mass density scaling relations for individual galaxies as they evolve from 1 Gyr lookback time. The correlation lines pivot around a log-stellar mass surface density of 7.25 [M⊙ kpc−2], which may be evidence of a self-regulating process on these scales. Radial profiles of the galaxy logarithmic specific SFR (sSFR) show an overall decrease over 1 Gyr, but five galaxies show a greater change in log(sSFR) at the outskirts than the center, indicating a possible early onset of quenching in these galaxies.

X-Ray Emission In Illustristng Circum-Cluster Environments: Ii. Possible Origins Of The Soft X-Ray Excess Emission, Celine Gouin, Daniela Galárraga-Espinosa, Massimiliano Bonamente, Stephen Walker, Mohammad Mirakhor, Richard Lieu, Clotilde Laigle, Etienne Bonnassieux, Charlotte Welker, Stefano Gallo, Tony Bonnaire, Jade Paste

Publications and Research

Context. An excess of soft X–ray emission (∼0.2 − 1 keV) above the contribution from the hot intracluster medium (ICM) has been detected in a number of galaxy clusters, including the Coma cluster. The physical origin of this emitting medium above the hot ICM has not yet been determined, in particular, it is unclear whether it is thermal or nonthermal.

Aims. We investigate the gas phase and gas structure that reproduce the soft excess radiation from the cluster core to the outskirts best using simulations.

Method. By using the IllustrisTNG simulation (TNG300), we predict the radial profile of thermodynamic properties …

Infinite Line, Infinite Knowledge: The 'Spera' And Organized Chaos In Lambert's Encyclopedia, The 'Liber Floridus', Ava Romano

Theses and Dissertations

The Liber Floridus is a medieval encyclopedia renowned for its program of circular diagrams, or sperae. Inside this manuscript of 190 chapters, these diagrams frame and embody written knowledge, revealing a connection between encyclopedism and life in the Benedictine monastery by creating a coherent visual organization of chapters.

The Density Distribution Of The Material Around Betelgeuse, Iman Behbehani

Dissertations, Theses, and Capstone Projects

Betelgeuse is a red supergiant star visible in the constellation Orion. Its windy and highly convective surface results in a complicated mass loss pattern difficult to understand and replicate in simulations. The ejected mass can form a shell around the star we consider the circumstellar material (CSM). In this study, we use ALMA interferometric observations to find the structure of Betelgeuse's CSM, and connect to the mass loss mechanisms that could form it. We measure a bipolar circumstellar structure with a position angle of 42.3$\pm 7.0^\circ$. We observe asymmetries in the form of hot spots in the north east of …

Leveraging Stellar Chemistry For A Global View Into The Atmospheres Of Brown Dwarfs And Giant Exoplanets, Emily Calamari

Dissertations, Theses, and Capstone Projects

In the era of the James Webb Space Telescope (JWST), it is now possible to examine substellar mass atmospheres in unparalleled detail and precision. However, unraveling the complicated thermodynamics and chemistry in these atmospheres remains a challenge. Atmospheric retrievals are a leading data-driven technique capable of recovering an object’s fundamental parameters such as mass, radius, effective temperature, gravity, cloud structure and composition and chemical abundances. However, in directly imaged or isolated worlds, constraining and/or interpreting these fundamental parameters can be difficult, particularly as retrieval models try to parameterize the overall impact of clouds.

For my dissertation, I turned to main …

Effect Of Equation Of State On The Formation Of Binary Black Holes In Active Galactic Nucleus Disks, Theodore Edwards

Dissertations, Theses, and Capstone Projects

Active galactic nucleus disks have been proposed as a possibly dominant location of the mergers of binary black holes detected by gravitational wave observatories. The nonlinear interactions between stellar mass black holes and disk gas determine when binaries will form from single objects on nearby orbits. Prior work has used smoothed particle hydrodynamics models in an isothermal disk to study this problem. However, the local equation of state near the midplane of an optically thick accretion disk is adiabatic rather than isothermal, even if the radiative equilibrium temperature is azimuthally isothermal. Therefore, we investigate the use of an adiabatic equation …

Satellite-Host Galaxy Co-Evolution With Next-Generation Regulator Models, Austen Gabrielpillai

Dissertations, Theses, and Capstone Projects

The evolution of satellites galaxies is an unsolved problem in galaxy formation. Recent observations such as the SAGA and ELVES surveys find tension in HI contents and star formation of satellites around their central host galaxies when compared to our own local environment, the Milky Way. These processes are potentially highly influenced by the host's circumgalactic medium (CGM), and to constrain these cases requires accurate and fast modeling of satellites-host interactions. In this work, we present our methodology for evolving z = 0 surviving satellites alongside their central galaxy in sapphire, a CGM regulator co-evolution model of galaxy formation. …

How To Form A Gravitational-Wave Source: Quantifying Intermediate Evolutionary Stages In Isolated Binary Stellar Evolution, Ana Lam

Dissertations, Theses, and Capstone Projects

Gravitational-wave (GW) detections from double compact object (DCO) mergers provide crucial observational constraints for understanding massive stars across cosmic time. Coupled with these observations, binary population synthesis simulations become powerful tools for probing the formation, evolution, and ultimate fates of their progenitors---massive binary stars. However, complex evolutionary pathways, shaped by key intermediate stages such as mass transfer phases and supernovae, present a significant challenge to assess their impact. To address this, we develop a framework to quantify the influence of intermediate evolutionary stages on GW sources. By combining Sankey diagrams with survival factors, we systematically investigate how intermediate stages influence …

Refining Orbits And Revealing Origins: A Study Of Giant Exoplanets Around Low-Mass Stars, Angeli Sandoval

Dissertations, Theses, and Capstone Projects

The study of gas giants around low-mass stars offers important insight into planet formation. Core accretion models predict that these planets should have a low likelihood of forming due to the limited disk masses of their host low-mass stars. However, NASA space missions such as Kepler and TESS have revealed an emerging population of Saturn- and Jupiter-like planets around M-dwarfs (referred to as giant exoplanets orbiting M-dwarfs or GEMS) that challenge these expectations. This thesis investigates the detection, confirmation, and analysis of GEMS through pipeline development and a detailed analysis of two systems.

In Chapter 1, I provide background information …

Novel Machine Learning Methods For Quasar Variability And Strong Gravitational Lensing, Joshua Fagin

Dissertations, Theses, and Capstone Projects

Machine learning methods are well suited to handle the unprecedented data volume expected from upcoming wide-field surveys. The European Space Agency's Euclid telescope was launched in July 2023 and is expected to observe billions of galaxies at high resolution, including tens of thousands of strongly lensed galaxies. The Rubin Observatory Legacy Survey of Space and Time (LSST) will monitor tens of millions of quasars throughout its ten-year lifetime, thousands of which will be strongly lensed. This flood of data will enable measuring lens galaxy mass distributions and substructure, as well as probing quasar accretion disk structure and black hole properties …

Investigating The Behavior Of Dwarf-Hosting Cosmic Filaments In Regions Of Average Density Within The Universe, Manuel E. Ramirez Hernandez

Dissertations, Theses, and Capstone Projects

The cosmic web is the large-scale structure of the universe, composed of elongated, overdense areas held together by gravity known as cosmic filaments. Within these filaments, dwarf galaxies are ubiquitous and make for excellent laboratories due to their small size. to determine the effects of cosmic web structures on dwarf galaxies. In this thesis, I laid the groundwork to investigate whether dwarf galaxy populations vary across different types of filaments. Filaments were extracted from the gas density field in the New Horizon simulation at $z=0$ using the topological feature finder DisPerSE. I determined the distances of galaxies to their nearest …

Geol 64: Planetary Geology - Syllabus, Dara Laczniak

Open Educational Resources

This Open Educational Resources (OER) syllabus is for an introductory planetary geology course that utilizes results from space missions to expose students to the surface features, composition, geological activity, and probable history of the planets, moons, asteroids, and comets of the solar system. It also places space exploration into the context of larger societal issues such as global warming and natural resource availability and addresses topics such as the ethics of space exploration and hazards of space travel. This OER syllabus aims to foster student-centered learning, critical thinking, data analysis and communication skills, and creativity. Assigned readings are compiled into …

Can We Discover Physical Models Using Machine Learning? A Case Study Of Galaxy Sizes, Festa Buçinca-Çupallari, Ariyeh Maller, Viviana Acquaviva, Austen Gabrielpillai, Rachel S. Somerville

Publications and Research

We explore the ability of machine learning methods to discover underlying equations of physics by searching for the equations governing galaxy size in a semianalytic model. This case study allows us to evaluate the process as we know the ground truth. We find that we fail to find an equation to predict galaxy size on the entire data set, but are successful when we separate out disk galaxies where we expect the physics driving galaxy size to be different than in bulge-dominated systems. We are also able to find an equation for bulge size, but not without adding an additional …

Artificial Intelligence And Astronomy: Lab Manual For Generative Ai-Based Learning Activities, Vasiliy Znamenskiy

Open Educational Resources

This lab manual introduces community college students to the intersection of artificial intelligence (AI) and astronomy through hands-on, inquiry-based activities. It explores how generative AI platforms—ranging from text-based chat systems to image and video generators—can enhance scientific understanding, creativity, and critical thinking in space science education. Students engage with tools such as ChatGPT, Gemini, DALL·E, and Synthesia to formulate and evaluate astronomy-related questions, generate scientifically inspired visualizations, and produce dynamic representations of cosmic phenomena. Through structured exercises, the manual promotes digital literacy, fosters analytical skills, and illustrates how AI assists in astronomical research, including data analysis, image enhancement, spacecraft autonomy, …

Integrating Universal Generative Ai Platforms In Educational Labs To Foster Critical Thinking And Digital Literacy, Vasiliy S. Znamenskiy, Joel Hernandez, Rafael Niyazov

Publications and Research

This study investigates the educational potential of generative artificial intelligence (GenAI) platforms based on large language models (LLMs), such as ChatGPT, Claude, and Gemini, as tools for studentcentred learning. Recognizing the current limitations of GenAI, particularly its propensity for generating inaccurate or misleading information—the paper proposes a novel instructional strategy: an interdisciplinary laboratory designed to foster critical evaluation of GenAI-generated outputs. In this pedagogical model, students engage with GenAI systems by posing questions or solving problems drawn from topics they have already studied and understand. Equipped with correct answers, students are positioned to assess the accuracy and relevance of AI-generated …

Fast Transients From Magnetic Disks Around Non-Spinning Collapsar Black Holes, Justin A. Bopp

Dissertations, Theses, and Capstone Projects

Most black holes (BHs) formed in collapsing stars have low spin, though some are expected to acquire a magnetic accretion disk during the collapse. While such BH disks can launch magnetically driven winds, their physics and observational signatures have remained unexplored. We present global 3D general relativistic magnetohydrodynamic simulations of collapsing stars that form slowly spinning BHs with accretion disks. As the disk transitions to a magnetically arrested state, it drives mildly relativistic, wobbling, collimated magnetic outflows through two mechanisms: steady outflows along vertical magnetic field lines (“Blandford-Payne jets”) and magnetic flux eruptions. With isotropic-equivalent energy of E_iso ≈10 …

Exploring The Enstatite Chondrites: Modal Abundances, Metamorphic History, And Volatile Challenges, Mabel Gray

Dissertations, Theses, and Capstone Projects

This thesis investigates the formation conditions, thermal histories, and volatile inventories of enstatite chondrites (ECs). A diverse set of ECs is analyzed to capture the broad variability within this meteorite class. Chapter 1 presents a comparative analysis of mineral abundances using automated point counting, X-ray diffraction analysis, and XMapTools-based phase mapping. The results reveal significant variations in silicate and sulfide abundances across EC groups, challenging the conventional binary classification and suggesting distinct formation conditions. Chapter 2 explores the thermal histories of two highly equilibrated EH chondrites, proposing a novel formation mechanism on the parent asteroid: contact metamorphism driven by an …

Streaming Instabilities In Class 0/I Disks, Shirin Gul Zaidi

Dissertations, Theses, and Capstone Projects

While it is clear that planets form in protoplanetary disks, fragmentation and the radial drift of pebbles inhibit the growth of grains to planetesimals. To overcome these barriers, effective localized dust clumping on a short enough time scale is required. One promising solution to this problem is the streaming instability. Streaming instability is only triggered with a large enough dust-to-gas ratio and grain size. Though it is unknown when and where those conditions are met in protoplanetary disks, recent studies have indicated that planetary cores likely require early formation to match detected exoplanet system masses, so that we need to …

Artificial Intelligence And Astronomy: Lab Manual For Generative Ai-Based Learning Activities, Vasiliy Znamenskiy

Open Educational Resources

This laboratory manual introduces an innovative approach to teaching astronomy by integrating generative artificial intelligence (AI) tools into hands-on educational activities. Aimed at undergraduate and general education students, the manual guides learners through interactive exercises that involve evaluating AI-generated text responses, creating scientifically inspired images, and producing short educational videos about astronomical phenomena. By engaging with platforms such as ChatGPT, Gemini, DALL·E, and InVideo, students develop critical thinking skills, enhance their digital literacy, and deepen their understanding of space science. The method emphasizes inquiry-based learning, creativity, and scientific communication, preparing students to become thoughtful users of AI in academic and …

Dual View Of The Z2-Gauged Xy Model In 3d, Piers Coleman, Anatoly Kuklov, Alexei Tsvelik

Publications and Research

The Z₂ gauged XY model is of long-standing interest both in the context of nematic order, and the study of fractionalization and superconductivity. This paper presents heuristic arguments that no deconfinement of the XY field occurs in this model and presents results of a large-scale Monte Carlo simulations on a cubic lattice which are consistent with this conclusion. The correlation radius determining the confinement is found to be growing rapidly as a function of the parameters in the phase featuring the nematic order. Thus, mesoscopic properties of the system can mimic deconfinement with high accuracy in some part of …

Classification Of Variable Stars Using Convolutional Neural Network, Abhina Premachandran Bindu

Dissertations and Theses

This research focuses on developing Convolutional Neural Networks (CNNs), for the process of classifying and identifying variable stars through the analysis of unprocessed light curves from Transiting Exoplanet Survey Satellite (TESS). As astronomical data is becoming increasingly complex, and as advanced missions deploy sophisticated instruments for data collection, both the quality and quantity of the data are improving at a rapid pace. This has created an urgent need to automate the analysis process using efficient and effective methods, such as those based on machine learning. While previous research has explored machine learning approaches, there has been limited focus on implementing …

Reconstructing Cosmic Filaments Around Dwarf Galaxies With The Rubin Observatory, Sarah E. Draves, Charlotte Welker, Charlotte Olsen

Publications and Research

The cosmic web is the largest structure in the universe, consisting of streams of gas and dust that connect galaxies made of stars, dark matter, and more gas and dust. Denser areas of the cosmic web tend to have more massive and redder galaxies, which implies a strong connection between cosmic structure and galaxy evolution. The degree to which galaxies are influenced by the cosmic web outside of relatively dense areas, particularly in the case of small filaments near galaxies, is still an area of active study. Low mass galaxies, known as dwarf galaxies, are particularly sensitive to the environment …

A Machine Learning Approach To Discovering Physical Models Of Galaxy Formation, Festa Bucinca

Dissertations, Theses, and Capstone Projects

Galaxies are the breathtakingly beautiful starry islands of the Universe. The process of galaxy formation involves the transformation from simple initial conditions in the early Universe to the complex galaxy structures we observe today. Spanning an immense spatial range and tremendous time scales - from the vastness of the Universe to the scale of individual stars - the physics of galaxy formation is both complex and crucial for understanding the Universe we live in. However, despite significant advancements, our theoretical understanding of galaxy formation remains incomplete.

In the era of big data available from hydrodynamical simulations and observations, Machine Learning …