Cosmological structure formation is dominated by an invisible, collisionless substance called dark matter, with a large subdominant component of baryons. Whereas dark matter only interacts gravitationally, baryons are affected by collisional, magnetic, nuclear, and relativistic processes. This makes full DM+baryon simulations exceedingly computationally expensive compared to Dark Matter Only (DMO) simulations. To fully understand structure formation without running such expensive simulations, baryonification codes are employed, modifying the output of DMO simulations to emulate baryonic effects. We present the results of a baryonification pipeline on a pair of mini-Ramses simulations, including implications for mock SZ Effect maps. We conclude, in agreement with literature, that baryonification codes are both necessary and sufficient for emulating the quantitative differences between dark matter and baryons, and comprise a promising new direction for computational cosmology.

We attempt to constrain the mass of the supermassive black hole (SMBH) in the center of the nearby late-type, quiescent, cold gas galaxy M95 (NGC 3351) using sub-millimeter CO emission line observations from the Atacama Large Millimeter Array (ALMA). The formation and development of galaxies and the mass and growth of SMBHs are closely tied, and the effectiveness of using SMBH masses to model galaxy evolution is highly dependent on how accurate the measurements are. This makes high-resolution sub-millimeter CO observations incredibly useful to accurately estimate the SMBH mass of late-type, cold gas-rich galaxies with a quiescent nucleus (where alternative methods with tracers other than CO cannot do so). Our dataset has a beam size of 0.1'' resolution with a 2.5 km/s spectral channel width, with a low noise floor of 1.5 K. Our CO(3-2) line detections near the black hole have integrated intensities near 2,000 K km/s, making our S/N ratio in the this region very high for modelling it against background. We used KinMS (KINematic Molecular Simulation) to model the central molecular torus surrounding M95's central SMBH, and after creating two models (one with a Keplerian velocity profile component and one without) and choose the results of the model that we are most confident matches the data. From this, we determined a hard upper limit that the mass of M95's central supermassive black hole is no greater than 6.543 x 10^5 solar masses given that we estimate that there is no more than that amount of dynamical mass within 0.1'' (or about ~5 pc) of the center of M95. We also determined a (less strict) upper limit that all central Keplerian mass in the center of M95 is at most ~3 x 10^5 solar masses (which could contain objects and structures other than the SMBH). Both upper limits are smaller than we would expect given the confirmed central SMBH masses of other galaxies, which gives us an interesting result that can be used to study how M95 might evolve differently from similar galaxies with classical bulges (which M95 does not have).

This thesis explores the direct detection prospects of the Cosmic Neutrino Background (CNB) and its implications for early Universe cosmology. We develop a theoretical framework for the behavior of nonzero mass neutrinos in a Friedmann-Lemaître-Robertson-Walker universe and calculate the properties of the CNB last scattering surface, showing that massive relic neutrinos originate from closer distances than photons from the CMB. Using constrained cosmological simulations using the 2M++ galaxy survey and the Bayesian Origin Reconstruction from Galaxies (BORG) inference algorithm, we analyze the clustering of relic neutrinos under the influence of large-scale structure formation. We present high- and low-resolution neutrino and dark matter density maps and predict variations in neutrino flux along known superclusters and voids. Our findings support the feasibility of mapping CNB anisotropies with experiments like PTOLEMY, highlighting the influence of gravitational clustering and quantum amplification mechanisms on relic neutrino detection rates. This work contributes to improving the theoretical and simulation groundwork necessary for the first direct observation of the relic neutrino background.

This thesis presents the development of a high school-level astrophysical sciences course, designed as an extracurricular for students with an interest in astronomy. Since astrophysics is rarely included in standard high school curricula, this set of lesson plans stands as an extracurricular option: an accessible, noncalculus-based entry point for students from diverse academic backgrounds. Its primary aim is not necessarily to prepare for advanced study, but rather to cultivate scientific literacy and understanding of core concepts of astrophysics, cross-cutting ideas, and real-world applications. This set of lesson plans is informed by contemporary pedagogical research, with an emphasis on student-centered learning and the use of play as a mode of academic engagement.

Hot Jupiters can be misaligned around stars with effective temperatures greater than ∼ 6100 K, and are seemingly always in alignment with stars cooler than this threshold. The high stellar obliquities of hot stars are thought to be left over from high primordial obliquities in hot Jupiter systems, due to the lack of a thick convective envelope in stars where Teff ≳ 6100 K, whereas inertial waves excited and dissipated in the convective envelopes of cooler stars may be able to tidally damp the obliquities of stars below this break. Such obliquity distributions have long been invoked as a potential channel of evidence for explaining the origins of hot Jupiters. We explore this theory through time evolutions of the relevant orbital and stellar parameters, implementing more realistic tidal evolution theory than previous explorations of this idea. We also consider the theory of core-envelope decoupling as a means of more easily tidally aligning systems by way of inertial wave damping. We find that there is no set of initial orbital, spin, and arrival parameters that can sufficiently reproduce the observed obliquity distributions of cool and hot stars simultaneously, and that core- envelope decoupling produces exceptionally strong damping of hot star obliquities and is thus starkly opposed to observations. We are unable to rectify observed obliquity distributions with theories of diverging stellar structures and inertial wave dissipation alone.

Carbon foils have been used in space physics flight instrumentation for decades, and they are the primary mechanism behind SWAPI, an instrument on NASA IMAP. SWAPI is designed to measure solar wind particles of H++ and He+. However, during coronal mass ejections or other solar events, a model of the carbon foil and the simulation of particles through it could predict how particles of different species interact with SWAPI. A Geant4 model of a carbon foil was created and compared against published multiple scattering data, where it aligned well with the experimental results. Then, this model was updated to fit the configuration of the Space Physics' Laboratory's absolute beam monitor (ABM). SIMION simulations of the ABM informed the development of its electric fields, and flight calibration data was used as a basis of comparison. The ABM model is not as accurate compared to the scattering data, and this is likely due to missing physics lists and processes, as Geant4 has limited options for low-energy physics. In the future, a full integration of SIMION with Geant4 geometry and physics can be pursued. Additionally, further research can be done to find the best low-energy physics lists for this application.

Past studies of turbulence in the Interstellar Medium (ISM) have simulated turbulent sources through the Fourier space driving (FSD). These studies have demonstrated that the resulting statistical distributions of the fluid are highly sensitive to the exact driving form, highlighting a need to analyze which form reproduces which aspects of the ISM. Real observations have shown regions of expanding bubbles commonly sourced by supernovae dominate the dynamic structure. This local source of turbulence is largely different from the global scale FSD method. To find regions in the FSD method that best reproduce the statistical distributions created by expanding bubbles, we compare both distributions outputted from MHD simulations. We utilized AthenaK, to which we’ve added a momentum bubble injection method. Our results show no FSD model is able to reproduce the resulting distributions of the momentum injection method. The velocity distributions are largely different between the two methods, with the momentum injection method generating larger power in the velocity field than all tested FSD models. We did find that both the purely compressive and momentum injection methods produce density distributions that are not log-normal. The momentum injection method possibly fits the log-normal distribution well largely, only deviating in low density non- Gaussian portions.

We characterize stellar, gas, and dark matter mass distributions for 17 nearby massive disk galaxies from the PHANGS sample. This allows us to compute the gravitational potential that vertically confines the interstellar gas and determines its equilibrium scale height and weight. We first combine dynamical mass constraints from existing CO and HI rotation curves together with stellar and gas mass estimates from near-infrared, CO, and HI data. These estimates incorporate current best practices in modeling stellar mass-to-light ratios and CO-to-H2 conversion factor variations. Then, we fit joint stellar–gas–dark matter mass models to the rotation curves, adopting the classic maximal disk assumption to account for remaining zero-point uncertainties on the stellar mass-to-light ratio. After obtaining three component radial mass profiles, we calculate the vertical equilibrium gas scale height and ISM weight in the combined gravitational potential. We find the gas scale height Hgas increases from ≲100 pc in the inner disks to >500 pc at large radii, consistent with observations of our Galaxy and other edge-on galaxies. The gas weight is dominated by stellar gravity at small radii, but the gas and dark matter gravity often become important beyond 3–6 times the stellar disk radial scale length. Both our gas scale height and weight estimates are dependent on the treatment of stellar disk scale height H⋆, with Hgas varying by 30–40% when H⋆ varies by a factor of 3. The relationship between our refined ISM weight estimates and local star formation surface density generally agrees with previous observations and predictions from theory and simulations.

Tidal disruption events (TDEs) are some of the brightest and most fascinating astronomical transients to behold. A passing or orbiting star may wander within the tidal radius of a supermassive black hole and be tidally ripped apart from the immense gravitational pull. Debris and remnants of the star then eventually accrete, producing brilliant flares and spectroscopic emission that can be observed. In this paper, I present a multi-epoch spectroscopic analysis of four TDEs—AT 2018hyz, AT 2018dyb, AT 2019qiz, and AT 2020zso—that aims to model the evolution of their accretion disks. My work focuses on modeling TDE emission profiles around the Hα λ6564 region at different epochs. In a small subset of TDEs, the accretion disk may emit broad, double-peaked lines that provide great insight into their properties, and these objects are the valued in my sample. The model of choice in this analysis is the axisymmetric, optically thick and geometrically thin, relativistic disk. Optimizing the parameters and understanding the accretion process unlock meaningful information about the supermassive black hole and in turn the host galaxy and its evolution throughout the universe.

Asteroseismology is an important tool for probing the fundamental characteristics of pulsating stars. Stellar oscillations are influenced by internal pressure, temperature gradients, and the structure of convective zones. Therefore, studying these oscillations enhances our understanding of stellar interiors. Research has shown that high mass main sequence stars exhibit strong pulsations. Theoretical models predict that low mass stars including M dwarfs can also pulsate at shorter periods and lower amplitudes. However, previous Kepler and K2 missions failed to detect convincing pulsations in M dwarfs likely due to a combination of instrumental limitations and the intrinsic faintness of the signals. In this work, we aim to identify solar like pulsations in low mass stars, particularly M dwarfs, using the Transiting Exoplanet Survey Satellite (TESS) 20 second cadence data. The high cadence and improved photometric precision of 20 second cadence data provide our best current opportunity to detect these faint pulsations especially in the low frequency, low amplitude regime where they are expected to occur. We extracted and analyzed light curves from our target stars to identify and characterize noteworthy signals. After processing the data, we used Lomb Scargle periodograms, power spectrum, and threshold analysis to investigate the nature of these signals. Our analysis revealed a variety of phenomena, including stellar flares, eclipsing binaries, variable stars, previously uncatalogued pulsations from nearby higher mass stars, and strong rotational modulation signatures in many of our targets.