Astrophysics and Astronomy Commons^™

Rings Of Ice, Erik Johnson

Natural Science Faculty

Have you ever seen the Milky Way? For most Americans, it is impossible to see the band of light from the galaxy outside their homes. To be able to experience the night sky as our ancestors did, we have to travel to places away from light pollution. International Dark Sky Week, which is happening April 22–30 this year, celebrates the night sky and offers everyone a chance to reflect on the lighting choices made around their home and in their community.

Search For Continuous Gravitational Waves From Known Pulsars In The First Part Of The Fourth Ligo-Virgo-Kagra Observing Run, A. G. Abac, R. Abbott, I. Abouelfettouh, F. Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas Villarreal, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Continuous gravitational waves (CWs) emission from neutron stars carries information about their internal structure and equation of state, and it can provide tests of general relativity. We present a search for CWs from a set of 45 known pulsars in the first part of the fourth LIGO–Virgo–KAGRA observing run, known as O4a. We conducted a targeted search for each pulsar using three independent analysis methods considering single-harmonic and dual-harmonic emission models. We find no evidence of a CW signal in O4a data for both models and set upper limits on the signal amplitude and on the ellipticity, which quantifies the …

Detection And Parameter Estimation Of Supermassive Black Hole Ringdown Signals Using A Pulsar Timing Array, Xuan Tao, Yan Wang, Soumya D. Mohanty

Physics & Astronomy Faculty Publications

Gravitational wave (GW) searches using pulsar timing arrays (PTAs) are commonly assumed to be limited to a GW frequency of ≲4 ×10−7  Hz given by the Nyquist rate associated with the average observational cadence of 2 weeks for a single pulsar. However, by taking advantage of asynchronous observations of multiple pulsars, a PTA can detect GW signals at higher frequencies. This allows a sufficiently large PTA to detect and characterize the ringdown signals emitted following the merger of supermassive binary black holes (SMBBHs), leading to stringent tests of the no-hair theorem in the mass range of such systems. Such large-scale …

Statistical Study Of Solar Wind Conditions Prior To Substorm Onsets, Luke H. Francis

Doctoral Dissertations and Master's Theses

Due to complex, multi-region, coupled plasma systems, auroral substorm onsets have been historically difficult to predict. The northward turning of the interplanetary magnetic field was considered the primary candidate as an external triggering mechanism for substorm onsets. However, that was later shown to be coincidental in nature. This study is motivated by recent multi-spacecraft observations that show how several magnetosheath jets at the bow shock were heavily correlated to substorm onsets, indicated by a strongly radial IMF interval. In the past, studies have looked at small samples of substorms in order to make large-scale predictions. However in this study, a …

Ligo Detector Characterization In The First Half Of The Fourth Observing Run, S. Soni, B. K. Berger, D. Davis, F. Di Renzo, A. Effler, T. Ferreira, E. Goetz, Francisco Llamas Villarreal, Volker Quetschke, J. Glanzer

Physics & Astronomy Faculty Publications

Progress in gravitational-wave (GW) astronomy depends upon having sensitive detectors with good data quality. Since the end of the Laser Interferometer Gravitational-Wave Observatory-Virgo-KAGRA third Observing run in March 2020, detector-characterization efforts have lead to increased sensitivity of the detectors, swifter validation of GW candidates and improved tools used for data-quality products. In this article, we discuss these efforts in detail and their impact on our ability to detect and study GWs. These include the multiple instrumental investigations that led to reduction in transient noise, along with the work to improve software tools used to examine the detectors data-quality. We end …

Ionospheric Evidence Of Lobe Reconnection For Northward Imf, Dora Csonge, Gerard Fasel, John Mann, Audrey Daucher, Owen Bradley, Aidan Hulbert, Thomas Lewer, Sun-Hee Lee, F. Sigernes, D. Lorentzen

Seaver College Research And Scholarly Achievement Symposium

It is believed that magnetic reconnection is one of the main mechanisms to transfer energy and momentum from the for the solar wind into the terrestrial environment. Dungey suggested that magnetic reconnection occurs on the dayside magnetosphere when the interplanetary magnetic field (IMF) is southward. Poleward moving auroral forms (PMAFs) have been identified in past studies as Ionospheric signatures of magnetic reconnection on the dayside.

However, magnetic reconnection can also occur for other geometrical orientations of the IMF. This presentation presents possible examples, 1 December 2021, for lobe reconnection during periods when the IMF x-component is negative, coupled with a …

Dayside Auroral Oval Expansion, Magnetic Flux Erosion, And Substorms, Dora Csonge, Parker Para, Gerard Fasel, Owen Bradley, Gasia Excel, Makena Swenski, Rachel Rodriguez, Sun-Hee Lee, John Mann, F. Sigernes, D. Lorentzen

Seaver College Research And Scholarly Achievement Symposium

Magnetic flux is eroded from the dayside magnetosphere when the interplanetary magnetic field (IMF) turns southward. During this period, the dayside auroral oval shifts equatorward as magnetic flux is transported anti-sunward to the magnetotail. Poleward-Moving Auroral Forms (PMAFs) are thought to be the ionospheric footprints of the flux tubes which are formed and transported tailward. Afterwards, magnetic reconnection occurs in the magnetotail, resulting in a substorm.

This study looks at the time between the onset of dayside magnetic reconnection and the onset of a substorm. Rates of dayside auroral oval equatorward shifts after southward turnings of the IMF are presented, …

Dayside North-South Aligned Auroral Arcs, Taiel Ramirez, Gerard J. Fasel, Wyatt Farrar, Mason Woolfolk, Andrea Black, Cullen Diggs, Clay Shin, Jordan Chiu, Sun-Hee Lee, John Mann, Fred Sigernes, Dag A. Lorentzen

Seaver College Research And Scholarly Achievement Symposium

Observations of North-South auroral arcs (or Sun-aligned) have been recorded for many years. Discrete North-South auroral arcs are located between 73-84° MLAT and are usually associated moderate auroral activity, low solar wind dynamic pressure, and a small IMF z-component. Some observations reported quasi-periodic poleward motions of North-South aligned dayside auroral arcs. This current statistical study contains nine years of All-Sky Camera images obtained from the Boreal Aurora Camera Constellation (BACC) from the Kjell Henriksen Observatory (KHO) in Longyearbyen, Svalbard (GEO: 78.148 N, 16.043 E; AACGM: 75.24 N, 111.21 E). The characteristics of discrete North-South dayside auroral arcs, including spatial and …

The Jwst Early Release Science Program For Direct Observations Of Exoplanetary Systems. Iii. Aperture Masking Interferometric Observations Of The Star Hip 65426 At 3.8 Μm, Shrishmoy Ray, Steph Sallum, Sasha Hinkley, Anand Sivaramkrishnan, Rachel Cooper, Jens Kammerer, Alexandra Z. Greebaum, Deeparshi Thatte, Tomas Stolker, Cecilia Lazzoni, Andrei Tokovinin, Matthew De Furio, Samuel Factor, Michael Meyer, Jordan M. Stone, Aarynn Carter, Beth Biller, Andrew Skemer, Genaro Suárez, Jarron M. Leisenring, Marshall D. Perrin, Adam L. Kraus, Olivier Absil, William O. Balmer, Anthony Boccaletti, Mariangela Bonavita, Mickael Bonnefoy, Mark Booth, Brendan P. Bowler, Zackery W. Briesemeister, Marta L. Bryan, Per Calissendorff

Astronomy: Faculty Publications

We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μm, as part of the JWST Direct Imaging Early Release Science program, obtained using the Near Infrared Imager and Slitless Spectrograph instrument. This mode provides access to very small inner working angles (even separations slightly below the Michelson limit of 0.5λ/D for an interferometer), which are inaccessible with the classical inner working angles of the JWST coronagraphs. When combined with JWST’s unprecedented infrared sensitivity, this mode has the potential to probe a new portion of parameter space across a wide array of astronomical observations. Using this …

Utilizing Machine Learning To Predict The Charge Storage Capability Of Lithium-Ion Battery Materials, Manoj Chhetri, Karen S. Martirosyan

Physics & Astronomy Faculty Publications

With the increasing demand for high-performance batteries in applications such as electric vehicles and portable electronics, accurately predicting the charge storage capacity of battery materials is crucial for developing more efficient and reliable energy storage systems. Machine Learning (ML) and data-driven approaches, plays a vital role in enhancing our understanding of Li-ion battery performance, guiding materials design, optimizing system efficiency, and accelerating innovation in energy storage technologies. In this study, an ML-based approach was applied to a dataset of 2345 rechargeable Li-ion battery materials, obtained from the Materials Project online portal, to predict gravimetric charge storage capacity ─ a key …

Three New 2+2 Quadruple Systems With Changing Inclination, Petr Zasche, Z. Henzl, M. Mašek, Jan Kára, H. Kučáková, J Merc, R. Uhlař

Physics & Astronomy Faculty Publications

We present a unique discovery of three new detected systems showing two different phenomena together. These are 2+2 quadruple stellar systems showing two eclipsing binaries as the inner pairs. And besides that, these systems were also found to exhibit the precession of the inner orbits causing the inclination changes manifesting themselves through the eclipse depth variations. We are not aware of any similar known system on the sky nowadays, hence our discovery is really unique. In particular these systems are: CzeV4315 = HD 228777 (periods 6.7391 and 0.91932 d, inclination change of pair B of about 1.4∘ yr−1); ASASSN-V J075203.23−323102.7 …

On Mach's Principle In General Relativistic Cosmological Models, Zach Zito

Student Research Symposium

General Relativity

1. Gravity is the mechanism by which matter influences inertia
2. This influence happens across a spacelike hypersurface
3. Geometrodynamic equations mathematically describe this influence

How It Will End: Physical And Philosophical Implications Of The Fate Of Our Universe, Alex Bittle '26

Honor Scholar Theses

What does physics have to say about the end of our universe? And what does it mean for us, if anything? Answering these questions requires an understanding of the so-called "lambda-cold dark matter" (ΛCDM) model of cosmology, which models the universe as containing an expanding pressure, Λ or dark energy, in a battle with the gravitational attraction provided by dark and regular matter. First, the physics (including observations and theory) of the ΛCDM, including the Big Bang and CMB, the inflationary period, and equations that govern the way the size of the universe changes with respect to time for different …

Parameter Estimation Of Binary Black Hole Coalescence Using Lstm Neural Networks, Lane Scheel

Undergraduate Honors Papers

The Advanced Laser Interferometer Gravitational Wave Observatory (aLIGO) made its first detection of gravitational waves in 2015. Since then, the rate of event detection has only increased, with a detection being made every 2-3 days during the current observing run, O4. This rapid influx of data has the potential to create bottle-necks in data analysis efforts, and can delay the scientific progress which require those efforts. Traditional gravitational wave data analysis techniques, such as matched filtering, require extremely large template banks of synthetic gravitational waveforms and can often fail to provide meaningful limits on system parameters. Not only is this …

Computational Modeling Of Astrophysical Systems, Leleya Iris Stallard

Spring Showcase for Research and Creative Inquiry

This research project focuses on the computational modeling of astrophysical systems using Femap with NX Nastran. The goal was to simulate and analyze the vibrational behavior and structural deformation of celestial bodies under different material compositions and collision conditions. Materials such as iron, granite, titanium, and models for white dwarf stars were used to investigate how varying physical properties affect the systems' dynamic responses. Both isotropic and anisotropic models were created to represent realistic astrophysical materials. Through static and modal analyses, the study explored how internal structure and material stiffness influence the reaction of celestial objects to applied forces and …

Planetary Atmospheres, Ryan M. Johnson

Physics Theses & Dissertations

Planetary atmospheres are frequently studied using a number of spectroscopic methods. One of these is observing spectra to analyze what molecules are present or chemical reactions may be taking place. To this end, we have produced a line list of the electronic a¹Δ−X³Σ⁻ and b¹Σ⁺−X³Σ− transitions of SO. Additionally, a line list pure rovibrational transitions of the a¹Δ and X³Σ⁻ states were produced, but lacked the necessary experimental data for the b¹Σ⁺ state. These line lists can be used in further …

Josephson Junctions: Fabrication And Applications For The Axion Dark Matter Experiment, Jonah M. Sachs

Senior Honors Papers / Undergraduate Theses

The observation of axions could revolutionize the world of physics. Through microwave frequency cavity readout of the photons associated with these axions, the ADMX project at WashU utilizes multiple different forms of the Josephson junction (JJ), a superconductive circuit element. The physics behind the JJ are essential to understanding its operation for resonant cavity readout in addition to parametric amplification. Parametric amplifiers produced using JJs can approach the signal-to-noise ratio set by quantum mechanics, and prove essential for the amplification chain used by the ADMX experiment for axionic detection. The limits of these amplifiers are set by the noise tuning …

Dual Quaternions For Gravity Recovery Missions, Ryan Kinzie

Doctoral Dissertations and Master's Theses

A dual quaternion-based modeling, state estimation and control approach is introduced as a better alternative to the traditional methods which are currently utilized for gravity recovery missions. The proposed modeling and control approach was verified against and compared to the tangent bundle to Special Euclidean Group 3 through MATLAB simulations. The dual quaternion-based approach shows superior performance over traditional linearized and uncoupled methodologies, in both modeling accuracy of spacecraft translational position, and the ability to control the pose of a test mass relative to its host spacecraft. Utilizing data products from the Gravity Recovery and Climate Experiment Follow-On mission, a …

19ne Excited States In Explosive Nucleosynthesis, Khang Pham

LSU Doctoral Dissertations

Classical novae and Type I X-ray bursts are stellar explosions that occur in binary systems, where nuclear reactions involving ¹⁹Ne play a crucial role in nucleosynthesis. In novae, the destruction of ¹⁸F via the ¹⁸F(p,alpha)¹⁵O reaction significantly affects the amount of ¹⁸F remaining in the ejecta, directly influencing the detectability of predicted 511-keV gamma rays. However, discrepancies between observed and predicted ¹⁸F abundances highlight uncertainties in the reaction rates, primarily due to unknown properties of resonances in the compound nucleus ¹⁹Ne. In Type I X-ray bursts, the ¹⁵O(alpha,gamma)¹⁹Ne reaction …

Measuring Cosmic Rays With Muon Detectors (Quarknet), Aiden Burton, Jack W. Maseberg

SACAD: Scholarly Activities

We report measurement of atmospheric muon particles originating from cosmic rays. Using four QuarkNet project scintillators in an unstacked geometry, we are counting muons in coincidence with each other. We are currently refurbishing a second detector apparatus and will soon be capable of measuring coincidence events for larger shower surface areas using a total of eight scintillators.