Astrophysics and Astronomy Commons^™

Decreasing Cross-Coupling In The Tianlai Radio Antenna Array, Nadia Marie Schwartz Bolef

Scripps Senior Theses

The 21-cm line is the electromagnetic radiation spectral line created by the change in energy state of neutral hydrogen atoms. This signal can be used for intensity mapping, a method of mapping the large-scale structure of the universe at different redshifts. However, challenges are being faced in the designing and building of the radio antenna arrays used to detect the 21-cm line signal. Currently, cross-coupling between antenna feeds is introducing beam errors and correlated noise that could overpower the signal. One possible solution we are working on is to use a phased array of antenna feeds instead of dishes and …

Constructing The 4th Hawc Catalog Of Very-High-Energy Sources Using An Automated Likelihood Pipeline Search, Samuel J. Groetsch

Dissertations, Master's Theses and Master's Reports

In this thesis, I present an analysis pipeline that allows one to search for and identify sources of very-high-energy (VHE) γ-ray emission in sky maps created from data collected with the High Altitude Water-Cherenkov (HAWC) Observatory. The HAWC Observatory is located at about 4100 m elevation just below Pico de Orizaba, the highest mountain in Mexico also known as Citlaltepetl (from the Nahuatl words citlal(in) = star, and tepetl = mountain). The observatory is an array of several hundred detector stations that measure signals from particle showers, so-called extensive air showers (EAS), that are initiated in interactions of primary cosmic …

The Computational Search For Unidentified Central Configurations Of The Newtonian N-Body Problem, Hannah G. Havel

CURE Proceedings

The N-body problem is a field of study in mathematics and physics that involves predicting the motion of particles moving under their mutual gravitational attraction. It is vital in celestial mechanics, such as planning collision-free satellite orbit trajectories. When beginning to understand the N-body problem, we can start by looking at equal masses of these particles or celestial bodies. As particles move, their position and velocity change, both energy and angular momentum are conserved. Sets of constant energy and angular momentum, known as integral manifolds, are higher-dimensional figures that represent constraints of movement to a system. Integral manifolds are described …

The Effects Of Environmental Factors On Tsunami Propagation And Inundation: A Comparison Of Earth With Other Planetary Bodies, Austin Halstead

All Master's Theses

Tsunamis are a universal hazard in any environment with oceans or lakes. Having a firm understanding of them is essential because of this. However, the vast number of tsunami studies have been solely on Earth, despite the growing evidence of oceans and lakes being on, or having once existed on, other planets and moons. In this study, I investigated tsunami behavior in non-Earth environments by testing the effects of varying viscosity and gravity. I conducted simulations using GeoClaw, Flow3D®, and VolcFlow on established tsunami benchmarks to identify consistent patterns in tsunami flow patterns and inundation. The results show …

Performance Optimization For A Scintillating Glass Electromagnetic Calorimeter At The Eic, J. Crafts, Renee H. Fatemi, T. Horn, D. Kalinkin

Physics and Astronomy Faculty Publications

The successful realization of the EIC scientific program requires the design and construction of high-performance particle detectors. Recent developments in the field of scientific computing and increased availability of high performance computing resources have made it possible to perform optimization of multi-parameter designs, even when the latter require longer computational times (for example simulations of particle interactions with matter). Procedures involving machine-assisted techniques used to inform the design decision have seen a considerable growth in popularity among the EIC detector community. Having already been realized for tracking and RICH PID detectors, it has a potential application in calorimetry designs. A …

Analysis Of Pulsar Discoveries And Pulse Profile Variability: From Pulsar Candidates To Gravitational Wave Detector, William Carl Fiore

Graduate Theses, Dissertations, and Problem Reports (ETD)

Last year, pulsar timing arrays (PTAs) reported evidence of a gravitational-wave (GW) background at nanohertz frequencies, opening a new window into the Universe. PTAs measure GW-induced variations in the timing of radio pulses from millisecond pulsars (MSPs) in our Galaxy. In order for PTA experiments to confidently detect and characterize the GW background, they must continue to regularly observe many MSPs and measure their pulse times of arrival as precisely as possible. This motivates efforts to find new MSPs with pulsar surveys, and to study pulsars whose unusual behavior may give rise to excess noise in PTA data sets, potentially …

An Observational Census Of Post-Merger Galaxies And Supermassive Black Hole Pair Evolution, Gregory Walsh

Graduate Theses, Dissertations, and Problem Reports (ETD)

Massive galaxy mergers are a fundamental consequence of the dynamic evolution of the Universe and play a central role in the evolution of galaxies. Because all massive galaxies harbor a central supermassive black hole (SMBH; M ≥ 10⁶ M_⊙), studying these merging systems with electromagnetic (EM) techniques constrains galaxy evolution models and provides a systematic means to examine the astrophysical mechanisms that facilitate the growth of SMBHs. These growing SMBHs are observable across the EM spectrum as Active Galactic Nuclei (AGN). Massive galaxy mergers are a natural formation mechanism for an SMBH pair, eventually evolving into an …

Molecules In Cool Stars: The A²Π - X²Σ⁺ And The B²Σ⁺ And The B²Σ⁺ - X²Σ⁺ Band Systems Of Cacl, Léo Lavy, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Cool red giant stars exhibit absorption bands of calcium monochloride (CaCl) in the optical region. In this work, the bands of CaCl corresponding to the A²Π − X²Σ⁺ transition with v′ ≤ 4 and v″ ≤ 4, and B²Σ⁺ − X²Σ⁺ transition with v′≤ 2 and v″ ≤ 2 are rotationally analyzed with PGOPHER, a multipurpose program for simulating and fitting molecular spectra. All bands were analyzed using high-resolution absorption spectra collected at the National Solar Observatory in 1985, calibrated with atomic lines from a high-resolution emission spectrum obtained …

Searching For Black Holes In The Galactic Center, Caden Zaccardi

Honors Undergraduate Theses

Due to the high extinction along the plane of the Milky Way towards the Galactic Center (GC), it is useful to look at objects that are bright in the near-infrared (near-IR) to obtain data with Earth-based instruments. To identify X-ray Binary (XRB) counterparts towards the GC, we used near-IR spectra from the Large Binocular Telescope (LBT). After reducing the LUCI/LBT spectra with the superFATBOY (sFB) pipeline, we compared our near-IR spectra to previously matched IR and X-ray sources in the GC (DeWitt, 2011). Particularly, we looked for H and He emission lines, which indicate signs of a hard radiation field …

A Multi-Wavelength Determination Of The Total Luminosity And Star Formation Rate Of The Milky Way, Joshua L. Mascoop

Graduate Theses, Dissertations, and Problem Reports (ETD)

The star formation rate (SFR) of the Milky Way is poorly understood in comparison to the SFR of other galaxies. In order to better find the Galaxy's place in the universe, it is imperative to understand the star formation activity occurring within it. We characterize the Galactic \hii\ region luminosity function (LF) at multiple infrared and radio wavelengths using a sample of 797 first Galactic quadrant \hii regions compiled from the WISE Catalog of Galactic \hii Regions. This sample is statistically complete for all regions powered by single stars of type O9.5V and earlier.

We find that neither a single …

A Hyperbolic Relaxation Solver For Numerical Relativity, Thiago Assumpcao

Graduate Theses, Dissertations, and Problem Reports (ETD)

Numerical relativity (NR) simulations are essential for self-consistently modeling compact binary mergers, whose observations form the heart of gravitational-wave science. Stable NR simulations are the result of mathematical and computational breakthroughs spanning several decades: early attempts to numerically solve the two-body problem in General Relativity (GR) date back to the 1960s, while the first successful black-hole binary merger simulations were performed in 2005 with the generalized harmonic coordinates, and in 2006 using the moving-puncture gauge.

Today, NR continues to drive progress in gravity research, with ongoing efforts focused on increasing physical realism in simulations containing matter, exploring alternative theories of …

The Search, The Localization, And The Characterization: Fast Radio Transients, Reshma Anna Thomas

Graduate Theses, Dissertations, and Problem Reports (ETD)

Fast radio transients are energetic bursts in centimeter or meter wave-lengths, lasting only milliseconds, and originating from both Galactic and extra-Galactic sources. In our Galaxy, these transients primarily originate from pulsars, which are rotating neutron stars. The more energetic extra-galactic transients, known as fast radio bursts (FRBs), have unknown origins. This thesis explores various techniques, including single dish and interferometric observations, to detect and accurately localize fast radio transients. It also investigates how the propagation effects of radio waves can reveal characteristics of the local environment and potential FRB sources. Furthermore, it demonstrates how FRBs can be used to study …

Hubble Tension And Gravitational Self-Interaction, Corey Sargent, William Clark, Alexander Deur, Balša Terzić

Physics Faculty Publications

One of the most important problems vexing the ΛCDM cosmological model is the Hubble tension. It arises from the fact that measurements of the present value of the Hubble parameter performed with low-redshift quantities, e.g. the Type IA supernova, tend to yield larger values than measurements from quantities originating at high-redshift, e.g. fits of cosmic microwave background radiation. It is becoming likely that the discrepancy, currently standing at 5σ, is not due to systematic errors in the measurements. Here we explore whether the self-interaction of gravitational fields in General Relativity, which are traditionally neglected when studying the evolution …

Fully Relativistic Derivation Of The Thermal Sunyaev-Zel'dovich Effect, Balša Terzić, Geoffrey A. Krafft, William Clark, Alexandre Deur, Emerson Rogers, Ioannis Sakiotis, Brandon Velasco

Physics Faculty Publications

We present the first fully and inherently relativistic derivation of the thermal Sunyaev-Zel'dovich effect. This work uses the formalism historically applied to compute radiation spectra emerging from inverse Thomson/Compton sources of x-ray radiation. Comparing our results to the traditional approach based on relativistically-corrected classical Kompaneets equation, we find small, but systematic differences. Most notable are the modest (⩽10%) differences in the crossover frequency where the spectral distortion due to the Sunyaev-Zel'dovich effect vanishes, and the quadratic scaling of the energy shift with the electron cloud temperatures.

Alfred Russel Wallace Notes 29. Extraterrestrial Entertainment: Are We Being Monitored By Alien Beings?, Charles H. Smith

Faculty/Staff Personal Papers

Alfred Russel Wallace (1823−1913) was an early advocate for the rational assessment of likelihood of extraterrestrial life. Current efforts to evaluate the situation have ranged from the heavily self-indulgent to the more objective, and it is still often difficult to decide just how much of the information we are receiving on the subject is dependable. An attempt is made here to cut through the haze and reduce the matter to elementals.

Conventions, Definitions, Identities, And Other Useful Formulae, Robert A. Mcnees Iv

Physics: Faculty Publications and Other Works

As the name suggests, these notes contain a summary of important conventions, definitions, identities, and various formulas that I often refer to. They may prove useful for researchers working in General Relativity, Supergravity, String Theory, Cosmology, and related areas.

Exploring The Hot And Gaseous Universe From Infrared To X-Ray, Chamani Gunasekera

Theses and Dissertations--Physics and Astronomy

Over 90% of baryonic matter in the universe exists as astrophysical plasmas. The gas
is often far from thermodynamic equilibrium, so numerical non-equilibrium spectral
synthesis simulations are used to understand observations. cloudy simulates vari-
ous physical conditions, providing spectra predictions. This thesis aims to meet the
challenge of new observatories like the JWST (James Webb Space Telescope) and
XRISM (X-Ray Imaging Spectroscopy Mission). These simulations are no better
than the underlying atomic and molecular database and the fourth chapter details
a long-needed update to an evolving database. The predicted spectra are strongly
affected by the composition of the gas, which …

Spinning Spheroidal Components Of Disk Galaxies: Resonant Interactions With Stellar Bars, Xingchen Li

Theses and Dissertations--Physics and Astronomy

The majority of disk galaxies possess stellar bars, which are the main driver in the internal evolution of barred galaxies. Bars represent non-axisymmetric perturbations in the galactic disks, producing strong gravitational torques that facilitate angular momentum transfer from the disk to the spheroidal components, such as central stellar bulges and host dark matter (DM) halos. The redistribution of angular momentum in barred galaxies proceeds mainly via resonant interactions between the bar and orbits in the spheroids. The amount of angular momentum emitted or absorbed at each resonance depends on the mass distribution, density and spin in the spheroidal components. Thus, …

Ratification Of The Base Of The Ics Geological Time Scale: The Global Standard Stratigraphic Age (Gssa) For The Hadean Lower Boundary, Janna Halla, Nora Noffke, Humberto Reis, Stanley Awramik, Andrey Bekker, Alexander Brasier, Flávia Callefo, Adrita Choudhury, Jan-Peter Duda, Christopher Fedo, Douglas Galante, Jessica Haddock, Peter Haines, Linda Hinnov, Axel Hofmann, Martin Homann, David Huston, Simon Johnson, Linda Kah, Martin Whitehouse, Et Al.

OES Faculty Publications

The base of the ICS (International Commission on Stratigraphy) Geological Time Scale was ratified in 2022 by defining a new Global Stratigraphic Standard Age (GSSA) for the lower boundary of the Hadean Eon (formerly 4000-3600 Ma); the age of the Solar System based on the oldest solids, calcium-aluminium inclusions (CAIs), generated in the protoplanetary disk. The formal GSSA for the Hadean base is the oldest reliable, weighted mean U-corrected Pb-Pb age of 4567.30 ± 0.16 Ma obtained for CAIs in primitive meteorites Allende and Efremovka. This age is supported by the 4568-4567 Ma U-corrected Pb-Pb ages of chondrules in Northwest …

The Present And Future Of Qcd, P. Achenbach, D. Adhikari, A. Afanasev, F. Afzal, C. A. Aidala, A. Al-Bataineh, D. K. Almaalol, M. Amaryan, D. Androić, W. R. Armstrong, M. Arratia, J. Arrington, A. Asaturyan, E. C. Aschenauer, H. Atac, H. Avakian, T. Averett, C. Ayerbe Gayoso, X. Bai, M. Zurek, Et. Al.

Physics Faculty Publications

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming …