Physical Sciences and Mathematics Commons^™

The Vvv Near-Ir Galaxy Catalogue Of The Southern Galactic Disc, M. V. Alonso, L. D. Baravalle, J. L. Nilo-Castellón, C. Villalon, M. Soto, M. A. Sgro, I. V. Daza-Perilla, C. Valotto, M. Lares, Lucas M. Macri

Physics & Astronomy Faculty Publications

Context. The distribution of galaxies in the zone of avoidance (ZoA) is incomplete due to the presence of our own Galaxy.

Aims. Our research is focussed on the identification and characterisation of galaxies in the ZoA, using the new near-infrared (NIR) data from the VVVX survey in regions covering the southern Galactic disc (230° <  l <  350°).

Methods. We used our previously established procedure, based on photometric and morphological criteria, to identify galaxies. The large data volume collected by the VVVX required alternatives to visual inspection, including artificial intelligence techniques such as classifiers based on neural networks.

Results. The VVV NIR galaxy …

12co Ro-Vibrational Spectroscopy Of Protoplanetary Disks: Inferring Planet-Disk Interactions, Janus Kozdon

All Dissertations

Observing and studying planets around young stars during their initial formation stages is essential for understanding the physics of their formation. Protoplanetary disks are the host sites of planets, and they exhibit substructures that hint towards the planets' presence, but the planet itself has rarely been detected. Analysis of the substructures in protoplanetary disks, especially towards the inner regions where most planets seem to lie, will provide information that can be used to refine theories about planet-disk interactions and, ultimately, planet formation. To probe the high-velocity inner regions, this study utilizes high-resolution spectroscopy, which has increased sensitivity with increasing velocities. …

Dissipation Physics And Absorption Features In Black Hole X-Ray Binaries, Theodore Dezen Phd, Benjamin R. Cavallari

McNair Summer Research Program

As matter falls closer toward the center of the accretion disk it loses gravitational potential energy, part of which becomes radiation primarily in X-ray wavelengths. Accretion disk models often invoked to fit observed spectra predict relativistically smeared absorption features that are not present in data from black hole X-ray systems such as GX 339-4 and LMC-X3. Informed by recent local and global simulations, we conduct new disk structure and radiative transfer calculations with increased dissipation rates of gravitational potential energy into thermal energy in disk upper layers. We find a noticeable reduction of the absorption features compared to older models …

Investigating Global Lightning Observed From Ground And Space, And Its Relationship To Solar Activity, Megan Diane Mark

Theses and Dissertations

The extremes of lightning, specifically lightning with long-lasting continuing currents and lightning with extremely high peak currents, are investigated from both ground- and space-based observations. Additionally, the potential solar influence on lightning is investigated on large spatial scales.

Continuing currents may occur following the impulsive flow of current during a cloud-to-ground (CG) return stroke and are usually low amplitude (from a few amperes to a few kiloamperes) and long duration (several to hundreds of milliseconds). Remotely estimating their duration from the electromagnetic fields measured by existing ground-based lightning locating systems (LLSs) is not possible, but some space-based lightning detection systems …

Dust Observations Of Occulting Galaxy Pair Vv 191., Clayton Robertson

Electronic Theses and Dissertations

The presence of dust grains as part of the the interstellar medium (ISM) in galaxies is an all-impactful entity in astronomy due its influence on light, and therefore observations. Unlike a true blackbody, dust absorbs, reflects, reddens, and scatters light within a line of sight. We quantify this phenomena with attenuation: the difference between the observed and true magnitudes of an astronomical object due to dust. Therefore, to map dust attenuation, one needs a known background source of light. In the serendipitous case of partially overlapping –occulting– galaxies, the background galaxy serves as the known light source and the transmission …

Development Of A New Groundbased Instrumentation Technique For Low-Resolution Exoplanet Transmission Spectroscopy, Mary Anne Limbach, Luke M. Schmidt, Ryan J. Oelkers, Darren L. Depoy

Physics & Astronomy Faculty Publications

We present a new instrumentation technique for high-precision, ground-based spectrophotometric measurements ideal for low-resolution (R ∼ 20–60) exoplanet transmission spectroscopy. This technique employs novel thin-film coating technology for wide-band, simultaneous multi-band imaging, enabling high-precision differential photometry through self-referencing and comparison stars. Theoretical calculations and on-sky results show that this method effectively reduces 96% of amplitude scintillation noise and other systematics that typically limit ground-based spectrophotometric precision for bright stars. On-sky results are demonstrated using the custom-built Exoplanet Transmission Spectroscopy Imager (ETSI), deployed at the McDonald Observatory 2.1 m telescope in 2022. For a V = 9.7 mag star, ETSI …

Chemical & Electromagnetic Signatures Of Binary Neutron Star Mergers, Benjamin Amend

All Dissertations

Binary neutron star (BNS) mergers are some of the most energetic events in the universe, producing both short gamma-ray bursts (GRBs) and kilonovae. GRBs are brief, bright flashes of gamma rays, powered by ultra-relativistic jets launched during the merger. These jets produce a prompt burst of gamma rays, followed by a broadband afterglow generated by external shocks as the outflow interacts with the surrounding medium. Kilonovae are optical-infrared transients from the radioactive decay of heavy, neutron-rich nuclei formed through the rapid neutron capture process (r-process) in the merger ejecta. Together, GRBs and kilonovae provide unique laboratories for probing fundamental physics …

Discovering High-Redshift Bl Lacs And Localizing Grbs For Mev Missions, Yong Sheng

All Dissertations

Blazars are active galactic nuclei (AGNs) with their jets aligned towards Earth. Gamma-ray bursts (GRBs) can be classified into long and short types. Long GRBs are produced by the collapse of massive stars, while short GRBs are formed by binary mergers (neutron star - neutron star or neutron star - black hole mergers). Both objects are the key probes of extreme physics processes and cosmic evolution, providing us an unique window to understand the Universe. My research aims to measure the redshift of blazars and localize GRBs for proposed and upcoming gamma-ray telescopes. BL Lac objects (BL Lacs) are a …

Thermally Tunable Mid-Infrared Nanocavity Resonance Of Coupled Surface Plasmon-Phonon Polaritons, Satya R. Kachiraju, Zachary M. Brown, Sundar Kunwar, Long Chang, Imtiaz Ahmad, Pinku Roy, Vladimir Kuryatkov, Yejin Kwon, Ayrton A. Bernussi, Chase T. Ellis

Physics & Astronomy Faculty Publications

Phase-change materials (PCMs) are essential for achieving tunability of metasurfaces. However, they frequently face limitations in the long-wave infrared range because of their lossy behavior. Here, we experimentally demonstrate a thermally tunable mid-infrared nanocavity resonance from coupled surface plasmon-phonon polaritons that are supported within a trilayer structure of metal-PCM layer-polar dielectric (Au-VO2-SiC). The top metal structures configure the Fabry-Perot cavity resonance near 840 cm−1 (11.9 µm), which is sensitively tunable and reversible with small changes in the VO2 refractive index ∆n near below its insulator-to-metal phase transition temperature where the loss is small. The maximum resonance shift of 7.7 cm−1 …

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

Estimating Galactic Structure Using Galactic Binaries Resolved By Space-Based Gravitational Wave Observatories, Shao-Dong Zhao, Xue-Hao Zhang, Soumya Mohanty, Màrius Josep Fullana I Alfonso, Yu-Xiao Liu, Qung-Ying Xie

Physics & Astronomy Faculty Publications

Space-based gravitational wave detectors, such as the Laser Interferometer Space Antenna (LISA) and Taiji, will observe GWs from O(108) galactic binary systems, allowing a completely unobscured view of the Milky Way structure. While previous studies have established theoretical expectations based on idealized data-analysis methods that use the true catalog of sources, we present an end-to-end analysis pipeline for inferring galactic structure parameters based on the detector output alone. We employ the GBSIEVER algorithm to extract GB signals from LISA Data Challenge data and develop a maximum likelihood approach to estimate a bulge-disk galactic model using the resolved GBs. We introduce …

Thermally Tunable Mid-Infrared Nanocavity Resonance Of Coupled Surface Plasmon-Phonon Polaritons, Satya R. Kachiraju, Zachary M. Brown, Sundar Kunwar, Long Chang, Imtiaz Ahmad, Pinku Roy, Vladimir Kuryatkov, Yejin Kwon, Ayrton A. Bernussi, Chase T. Ellis

Physics & Astronomy Faculty Publications

Phase-change materials (PCMs) are essential for achieving tunability of metasurfaces. However, they frequently face limitations in the long-wave infrared range because of their lossy behavior. Here, we experimentally demonstrate a thermally tunable mid-infrared nanocavity resonance from coupled surface plasmon-phonon polaritons that are supported within a trilayer structure of metal-PCM layer-polar dielectric (Au-VO2-SiC). The top metal structures configure the Fabry-Perot cavity resonance near 840 cm−1 (11.9 µm), which is sensitively tunable and reversible with small changes in the VO2 refractive index ∆n near below its insulator-to-metal phase transition temperature where the loss is small. The maximum resonance shift of 7.7 cm−1 …

Using Moment Maps To Observe Hydrogen Gas In Markarian 54, Amaya Terry

Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal

Hydrogen gas is useful when trying to understand galaxies because it helps make stars. In space, hydrogen gas is in many cases in a form called neutral hydrogen (HI). This gas emits a faint type of light called the 21 cm line, which is a type of radio wave. This light is useful because it can go through dust in space, unlike optical light. This means we can use it to look inside galaxies and study the gas even if there is dust that is in front of stars in the galaxy.

In my research I was given data from …

Survey Of Possible Magnetic Field Sources Around The Intragroup Medium Of Ngc 2563, Edward A. Wallace, Anna Williams

Macalester Journal of Physics and Astronomy

The origin and evolution of magnetic fields in space is an ongoing mystery in astronomy. Previous work has concluded the existence of magnetic fields in galaxy clusters, and to build an evolutionary model, the motivation behind this project is to determine how these magnetic fields form. In order to answer this question, we want to search for magnetic fields in galaxy group NGC 2563. To do this, our project determines the contribution to observed rotation measures of the galaxy group that come from the Milky Way and from the sources themselves.

Modelling Of The Overcontact Eclipsing Binary V826 Aur, Kalev T. Murray-Rouse, John M. Cannon, Anna Williams, Wes Tobin

Macalester Journal of Physics and Astronomy

We present a model of the eclipsing binary system V826 Aur using differential photometric data from the Robert L. Mutel Telescope (RLMT) at the Winer Observatory in Sonoita, Arizona. The calculated time of superconjunction was found to be 60648.7658534 and the period was 0.361701 d. These values were used to generate a best-fit model of the eclipsing binary with the PHOEBE program. The best-fit modelled parameters were found to be: mass ratio (𝑞) is equal to 2.769, the inclination (𝑖) is equal to 80.45◦, the fillout factor (𝑓) equals 0.0961, and the temperature ratio (𝑇2∕𝑇1) is 0.9740. Although not statistically …

Finding High Mass X-Ray Binaries In Ngc 3109, Caeden Miller, John (Jay) Gallagher Iii

Macalester Journal of Physics and Astronomy

High Mass X-Ray Binary systems can be difficult to find in the Milky Way due to high metallicity contributing to mass loss due to stellar wind, so we turn our attention to the galaxy NGC 3109 in order to find these systems. Using archival data from the Hubble Space Telescope using the Wide Field Camera 3, we do photometry in both the F475W and F814W filters for the two fields of view that cover the galaxy. We then plot these magnitudes on a color-magnitude diagram and use isochrones of 5 and 10 million years to gather minimum mass estimates of …

Making And Breaking Chaos: Analog Computer Implementation Of The Lorenz Model, Reed Lefevre, James Doyle

Macalester Journal of Physics and Astronomy

Hybrid analogue-digital computers have been shown to have certain advantages over traditional digital computers when solving nonlinear partial differential equations. Motivated by this fact, we implement the Lorenz equations on an analogue electronic computer and vary the parameters to analyze the bifurcations. With the working circuit, we compared experimental results to various digital simulations to assess the effectiveness of our circuit. We find clear qualitative agreement between the physical circuit and digital simulations; however, we observe a noticeable quantitative difference in behavior. The circuit depicts a picturesque Lorenz Butterfly plot and bifurcates into fixed points and chaos; however, these bifurcations …

Non-Destructive Compositional Analysis Of Lead Halide Perovskite Films Using Thz Spectroscopy And A Three-Oscillator Dielectric Model, Isaac J.C Kisker

Macalester Journal of Physics and Astronomy

Terahertz (THz) Spectroscopy offers a novel approach to probing low-energy phonon excitation in complex crystalline materials like methylammonium lead iodide (MAPI) perovskite films. In this research, we use time-resolved Terahertz Spectroscopy in tandem with a three-oscillator model to non-destructively ascertain the relative volumetric composition of MAPI and residual lead iodide (PbI₂) in spin-coated films. The dielectric function is modeled as a product over longitudinal and transverse optical phonon modes. This model is then fitted to the measured THz spectra, allowing us to extract the contributions from both MAPI and PbI₂.

Examining Mulit-Wavelength Variability And Magnetic Interactions In The Polar St Lmi, Cain Rinkoski

Macalester Journal of Physics and Astronomy

Cataclysmic variable (CV) stars are interacting binary systems that exhibit exotic, multi-wavelength behavior driven by mass transfer from a donor star onto a white dwarf. As rich laboratories for accretion physics, binary dynamics, and the origins of Type Ia supernovae, CVs have been well studied in the X-ray, ultraviolet, optical, and infrared—but remain comparatively underexplored in the radio regime. This paper presents simultaneous, time-resolved optical and radio observations of the magnetic CV ST LMi, aimed at constraining its emission mechanisms and orbital modulation.
The optical light curves display brightness variations of approximately 1.31 ± 0.02 magnitudes on a period of …

A Thermal Control System For The Atlas Hgtd Module Construction Process, Keelin B. Murphy

Macalester Journal of Physics and Astronomy

In the aim of simplifying the production process of 2000 HGTD (High Granularity Timing Detector) modules at IJClab for the high luminosity phase of the ATLAS experiment at the CERN Large Hadron Collider, I designed, coded, and constructed an automatic temperature control system for module assembly and testing. To this end, I examined the module’s thermal response to changes in air temperature using a climate chamber and to various currents fed through a Peltier device situated under the module. I adapted the Peltier setup into a fully independent control system driven by an Arduino microcontroller running a PID feedback loop.

Dose Characterization Of Galactic Cosmic Rays In The Human Brain: A Phits-Based Study With A Segmented Anatomical Phantom, Shanice N. Manning

LSU Master's Theses

Astronauts aboard the International Space Station (ISS) are chronically exposed to a complex space radiation environment composed of galactic cosmic rays (GCR), solar particles, and Earth's trapped radiation. These high-energy particles interact with spacecraft shielding, producing secondary particles that can penetrate inside and deposit energy in sensitive tissues. Although animal studies have been useful in assessing space radiation risks, anatomical and physiological differences limit their applicability to human anatomy especially neuroanatomy. To address this gap, we developed a computational framework to model radiation dose distribution within the human brain using Monte Carlo simulations in Particle and Heavy Ion Transport code …

Making Observations, Erik Johnson

Natural Science Faculty

After years of planning and construction, the NSF-DOE Vera C. Rubin Observatory has collected its "first light" from space, and the first images have been released to the public.

The Search For Magnetar Giant Flares In Archival Gamma-Ray Burst Data To Constrain Their Rates And Energetics, Aaron Trigg

LSU Doctoral Dissertations

Magnetar giant flares are rare, extremely bright bursts of gamma-rays from highly magnetized neutron stars. These events are difficult to identify because, at extragalactic distances, they can appear similar to other astrophysical phenomena. Only a handful have been confidently identified to date, limiting our understanding of their origin and physical properties. This dissertation focuses on expanding the sample of known events and enabling a more detailed characterization of their observational features. We report on two newly identified examples, GRB 180128A and GRB 231115A, that are consistent with a magnetar origin based on their spectral properties and association with nearby star-forming …

A Wide-Field Map Of Ultracompact Dwarfs In The Coma Cluster, Richard T. Pomeroy, Juan P. Madrid, Conor R. O’Neill, Alexander T. Gagliano

Physics & Astronomy Faculty Publications

A data set of 23,351 globular clusters (GCs) and ultracompact dwarfs (UCDs) in the Coma cluster of galaxies was built using Hubble Space Telescope Advanced Camera for Surveys data. Based on the standard magnitude cut of MV ≤ −11, a total of 523 UCD candidates are found within this data set of compact stellar systems (CSS). From a color–magnitude diagram analysis built using this catalog, we find a clear mass–magnitude relation extending marginally into the UCD parameter space. The luminosity function defined by this data set shows an excess of sources at bright magnitudes, suggesting a bimodal formation scenario …

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 …

Electroexcitation Of Nucleon Resonances And Emergence Of Hadron Mass, Patrick Achenbach, Daniel S. Carman, Ralf Gothe, Kyungseon Joo, Victor I. Mokeev, Craig D. Roberts

Faculty Publications

Developing an understanding of phenomena driven by the emergence of hadron mass (EHM) is one of the most challenging problems in the Standard Model. This discussion focuses on the impact of results on nucleon resonance (N*) electroexcitation amplitudes (or γ_vpN*) obtained from experiments during the 6 GeV era in Hall B at Jefferson Lab on understanding EHM. Analyzed using continuum Schwinger function methods (CSMs), these results have revealed new pathways for the elucidation of EHM. A good description of the Δ (1232) 3/2⁺, N (1440) 1/2⁺, and Δ (1600) 3/2^{+ …}

Investigating Long-Lasting Meteor Train Phenomena In Optical And Radio Regimes, Logan E. Cordonnier

Physics & Astronomy ETDs

Throughout history, meteors have been regarded as fascinating and portentous events, with bygone astronomers diligently recording their occurrence. The research presented herein continues in this tradition, using modern instruments, software, and data reduction techniques to study long-lasting meteor trail phenomena, specifically in the optical (persistent trains; PTs) and radio (meteor radio afterglows; MRAs) regimes. The overarching goal was to investigate the similarities between these phenomena, which began with the creation of a PT catalog. Many of the prior assumptions about the nature of PTs were found to be unsubstantiated, and several new behaviors were uncovered. This includes the discovery of …

Detecting Ionospheric Disturbances Using High Frequency Coastal Radar Transmissions From The West Coast Of The United States, Riley N. Troyer, Kenneth Obenberger, Michael Negale, Eugene Dao, Zsolt Balint, Eric Burnside, Kris Robinson, Jeffrey M. Holmes, Pavel Inchin, Jonathan Snively

Space Dynamics Laboratory Publications

Coastal radar system are located around the world and many happen to transmit at frequencies capable of skywave propagation via the ionosphere. Therefore, they can be detected hundreds to thousands of kilometers away. This paper demonstrates the opportunity to detect 39 Coastal Ocean Dynamics Application Radar transmitters located on the western coast of the United States using three HF radio receivers in Utah and New Mexico. It also illustrates the possibility to use the phase and Doppler measurements of these signals to derive displacements of the refracting ionospheric layer up to meter resolution for the 2023 annular solar eclipse, an …

Hot Donors In Cataclysmic Variables: The Case Of Ei Psc, Jan Kára, S. Zharikov, M. Wolf, N. Vaidman, A. Agishev, S. Khokhlov, C. E. Chavez

Physics & Astronomy Faculty Publications

Context. We present results of time-resolved optical spectroscopy and photometry of the short-orbital period dwarf nova EI Psc.

Aims. This study aims to determine fundamental system parameters of EI Psc, study properties of accretion structures in the system, and investigate its origin and current evolution state.

Methods. We analyse newly obtained time-resolved spectroscopic and photometric observations as well as archival data. We used light curve modelling, Doppler tomography, and MESA evolutionary models to study the characteristics of EI Psc.

Results. The system contains a relatively low temperature (T_eff = 6130 K) white dwarf with mass of M …

Understanding Stellar Element Formation Through Nuclear Reactions, Irena Langer, Mally Panek, Kiyah Young-Wilson, Adam Fritsch

Physics Student Scholarship

Studying nuclear structure has many applications, such as developing a stronger understanding of stellar nucleosynthesis, or how elements are formed inside of stars. Our research focuses on analysis of the proton evaporation nuclear reaction of Carbon-12 on Aluminum-27 in order to extract information about the structure of the nuclei involved. We are studying the cross section, or likelihood, of this reaction, using both experimental and modeled data. Since the cross section of a nuclear reaction depends on the physical characteristics of the nuclei involved, we can use the cross section to analyze our work.