Physical Sciences and Mathematics Commons^™

Sub-Chandrasekhar Type Ia Supernovae Scenarios With Increased Pathways For Neutronization, Fernando Hernan Rivas

Doctoral Dissertations

Type Ia supernovae are thermonuclear explosions of white dwarfs (WD), electron-degenerate cores of old intermediate mass stars(under 8$M_{\odot}$). Reaching energies of $10^{51}$\si{\erg}, they outshine whole galaxies as they synthesize and distribute most of the iron group elements (IGE; V, Cr, Mn, Fe, Co, Ni) into the interstellar medium, thus being one of the main agents in cosmic chemical evolution. Also, given their notably homogeneous lightcurves, they form the last step in the cosmic distance ladder outdistancing Cepheid variables by orders of magnitude. Though calibration of said lightcurves is dependent on a high number of confirmed events, the limits of statistical …

Analysis Of A Controlled Approximation For Explicit Integrations Of Stiff Thermonuclear Networks, Nicholas Brey

Masters Theses

The current standard method to solve stiff coupled differential equations relies on implicit integration methods. Explicit methods are generally avoided due to the extremely small and limiting timesteps they allow when the equations are stiff. However, implicit methods are computationally expensive because of the complex calculations that need to be done at each time step. An explicit integration method can do these calculations quicker and, if allowed to take comparable timesteps to the implicit ones, would allow the entire calculation to be done faster. Previous work by Dr. Guidry, Dr. Endeve, Dr. Hix and Dr. Billings has shown that, in …

Core-Collapse Supernova Simulations With Spectral Two-Moment Neutrino Transport, Ran Chu

Doctoral Dissertations

The primary focus of this dissertation is to develop a next-generation, state-of-the-art neutrino kinetics capability that will be used in the context of the next-generation, state-of-the-art core-collapse supernova (CCSN) simulation frameworks \thornado\ and \FLASH.\index{CCSN} \thornado\ is a \textbf{t}oolkit for \textbf{h}igh-\textbf{or}der \textbf{n}eutrino-r\textbf{ad}iation hydr\textbf{o}dynamics, which is a collection of modules that can be incorporated into a simulation code/framework, such as \FLASH, together with a nuclear equation of state (EOS)\index{EOS} library, such as the \WeakLib\ EOS tables. The first part of this work extends the \WeakLib\ code to compute neutrino interaction rates from~\cite{Bruenn_1985} and produce corresponding opacity tables.\index{Bruenn 1985} The processes of emission, …

Extending Core-Collapse Supernova Simulations: From The Onset Of Explosion To Shock Breakout, Michael A. Sandoval

Doctoral Dissertations

A core-collapse supernova (CCSN) is the result of a massive star’s core collapsing due to the inability of electron degeneracy pressure to provide sufficient support against gravity. Currently, there is a disconnect between when most three-dimensional CCSN simulations end (seconds) and when the explosion would reach the surface of the star and become visible (hours to days). We present three-dimensional simulations of CCSNe using the FLASH code that follow the progression of the explosion to the stellar surface, starting from neutrino-radiation hydrodynamic simulations of the first seconds performed with the Chimera code. We consider a 9.6-M_⊙ zero-metallicity progenitor, starting …

Study Of 134in Beta-Delayed Neutron Emission And Development Of A New Generation Neutron Detector, Joseph Heideman

Doctoral Dissertations

Beta-delayed neutron emission in very neutron-rich nuclei plays an essential role in nuclear structure and the understanding of the astrophysical r-process. A complete description of this process requires knowledge of both steps, beta decay and neutron emission. A leading theory poses the intermediate daughter nucleus to behave as a compound nucleus. The conditions for beta-delayed neutron emission of 134In are not well described by the assumptions in the neutron pandemonium hypothesis, therein providing a unique case to this process due to the proximity to 132Sn. Single-particle states in 133Sn obvserved after neutron emission have dissimilar shell occupancy compared to neutron-hole …

Expanding Band Parameter Analysis Methods For Hed Meteorites And V-Type Asteroids, Noah Adm Haverkamp Frere

Masters Theses

Vesta and Vesta-like asteroids have been convincingly linked, through visible and near-infrared (VNIR; 0.7 - 2.5 µm [micron]) spectral analysis, to a clan of basaltic achondritic meteorites – howardites, eucrites, and diogenites (HEDs). VNIR reflectance spectra of V-type asteroids and HED meteorites have two absorption features centered near 1 µm (Band I) and 2 µm (Band II) caused primarily by Fe²⁺ [iron] and Ca²⁺ [calcium] cations in pyroxene. Previous studies have shown a correlation between the mol% Fs and Wo with the central wavelengths of Band I and Band II, hereafter called Band I Center (BIC) and Band …

Probability Distribution Of Equations Of State For Astrophysical Simulations, Xingfu Du

Doctoral Dissertations

The detection of gravitational wave during the neutron star merger event GW170817 greatly enhanced our ability to probe the interiors of neutron stars. Future measurements of similar events will put further constraints to the equation of state (EOS) of nuclear matter. Also, uncertainties in the EOS create variations in the results of astrophysical simulations of core-collapse supernovae and neutron star mergers. In order to quantify the uncertainties, we construct a probability distribution of equations of state (EOSs). We create a new EOS which respects experimental, observational and theoretical constraints on the nature of matter in various density and temperature regimes. …

Early Warning Solar Storm Prediction, Ian D. Lumsden, Marvin Joshi, Matthew Smalley, Aiden Rutter, Ben Klein

Chancellor’s Honors Program Projects

No abstract provided.

Thornado-Hydro: Generalizing Discontinuous Galerkin Methods For A Nuclear Equation Of State For Supernova Hydrodynamics, Brandon Lynn Barker, Eirik Endeve, Anthony Mezzacappa

Chancellor’s Honors Program Projects

No abstract provided.

Using Atran Telluric Correction To Investigate The 3Μm-Region, Lucas Trent Mcclure

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

Small-bodies of the Solar System, such as asteroids, provide an abundant amount of information about planetary formation and evolution. In particular, the characterization of asteroids is vital to understanding the distribution and abundance of water throughout the Solar System. Recent findings in asteroid spectroscopy have provided evidence for the surface presence of water-ice and hydroxide, likely due to silicates on asteroid surfaces interacting with H⁺ ions from the solar wind. To investigate surface hydration, astronomers analyze the 3µm region, where an absorption feature is exhibited. Atmospheric water, however, affects the quality of the data around this particular region, but …

Surface Modification Of Icy Satellites: Space Weathering Of The Large Moons Of Uranus And Alluvial Fan Formation On Saturn’S Moon Titan, Richard John Cartwright

Doctoral Dissertations

The surfaces of icy satellites are continually modified by space weathering and geologic processes. This dissertation explores the processes changing the surface compositions of the large moons of Uranus and mechanisms for development of possible alluvial fans on the Saturnian moon, Titan. On the Uranian satellites, I hypothesize that the origin and distribution of carbon dioxide ice results from charged particle bombardment, and that spectrally red material originated on retrograde irregular satellites. On Titan, I hypothesize that landforms identified as alluvial fans at low and mid latitudes were formed by sheetfloods, whereas possible alluvial fans at high latitudes were formed …

Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory

Chancellor’s Honors Program Projects

No abstract provided.

Remote Neutron Spectroscopy On Mars, Christopher Gayle Tate

Doctoral Dissertations

Remote neutron spectroscopy is an important technique in planetary science that allows for classification of the amount of light elements in a planetary regolith. It is especially suited for studying hydrogen abundances and elements with high thermal neutron absorption cross sections in the top ~1 meter of regolith. The Mars Science Laboratory rover Curiosity carries the first rover based neutron spectrometer Dynamic Albedo of Neutrons (DAN) in Gale crater, Mars. As the DAN instrument operates in passive mode, it is sensitive to neutrons produced through Galactic Cosmic Ray interactions and neutrons generated by the rover's Multi-Mission Radioisotope Thermoelectric Generator. In …

Surface Plasmon Modes In Toroidal Nanostructures And Applications, Marouane Salhi

Doctoral Dissertations

A special interest in Plasmon mode resonance in toroidal nano-particles where a full and comprehensive analytical investigation is presented for different toroidal nano-structure within the quasi-static approximation. Then the optical response of gold nanorings and the associated near-field mapping when exposed to a broadband electromagnetic wave were obtained by the implementation of numerical methods to solve for the transient response. The numerical and analytical investigation lead to the design of an optical nano-trapping system and the identification of strong coupling interaction between toroidal plasmons and J-aggregate dye molecules a promising component in the design of novel optoelectronic material.

Nucleosynthesis In Core-Collapse Supernovae, Rachel E Mersch

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

A Core-Collapse Supernova explosion occurs when nuclear fusion stops in the core of a massive star. Without a source of energy supplying enough pressure to balance gravity, the core becomes unstable and collapses to form a neutron star. Beyond the neutron star, a shockwave forms which moves outward through the star, causing heavier elements to be created through nuclear fusion. We have been studying the elements that are ejected from a Core-Collapse Supernova using a nuclear code network called XNet, which follows the thermonuclear kinetics. We use the results from a code called Chimera, which explores the mechanism of Core-Collapse …

Solar Modulation Of The Cosmic Ray Intensity And The Measurement Of The Cerenkov Reemission In Nova’S Liquid Scintillator, Philip James Mason

Doctoral Dissertations

The NOνA (NuMI Off-axis electron neutrino Appearance) experiment is a long baseline neutrino oscillation experiment at Fermi National Accelerator Laboratory. Its purpose is to observe the oscillation of ν_μ (muon neutrino) to ν_e (electron neutrino) and to investigate the neutrino mass hierarchy and CP violation in the neutrino sector. Two detectors have been built for this purpose, a Near Detector 300 feet underground at Fermilab, and a Far Detector, on the surface at Ash River, Minnesota.

The completion of NOνA’s Far Detector in October 2014 enabled not only the recent measurement of neutrino oscillations, but an array of …

Neutrino Signatures In Terrestrial Detectors From Two- And Three-Dimensional Core-Collapse Supernovae Simulations, Tanner Brooks Devotie

Masters Theses

Core-collapse supernovae (CCSNe) are driven by neutrino emission and are the most prodigious sources of neutrinos in the Universe. Importantly, the neutrino radiation from CCSNe is emitted from deep in the explosion and can provide information about physical processes taking place in the newly-born neutron star at the heart of the event. We examine the four-flavor (i.e. ν_e, ν_e, ν_x and ν_x) [electron, muon and tau neutrinos along with their anti-matter counterparts] signature of CCSNe neutrino emission in various neutrino detector types. We use data from the multidimensional Chimera (Lentz et al., 2015) …

On The Spin Evolution Of Isolated Pulsars, Oliver Quinn Hamil

Doctoral Dissertations

Neutron stars are the remnants of supernova explosions, and harbor the densest matter found in the universe. Because of their extreme physical characteristics, neutron stars make superb laboratories from which to study the nature of matter under conditions of extreme density that are not reproducible on Earth. The understanding of QCD matter is of fundamental importance to modern physics, and neutron stars provide a means of probing into the cold, dense region of the QCD phase diagram.

Isolated pulsars are rotating neutron stars that emit beams of electromagnetic radiation into space which appear like lighthouses to observers on Earth. Observations …

The Effects Of Realistic Nuclear Kinetics, Dimensionality, And Resolution On Detonations In Low-Density Type Ia Supernovae Environments, Thomas L. Papatheodore

Doctoral Dissertations

Type Ia supernovae are most likely thermonuclear explosions of carbon/oxygen white dwarves in binary stellar systems. These events contribute to the chemical and dynamical evolution of their host galaxies and are essential to our understanding of the evolution of our universe through their use as cosmological distance indicators. Nearly all of the currently favored explosion scenarios for these supernovae involve detonations. However, modeling astrophysical detonations can be complicated by numerical effects related to grid resolution. In addition, the fidelity of the reaction network chosen to evolve the nuclear burning can alter the time and length scales over which the burning …

Nucleosynthesis In Self-Consistent Core-Collapse Supernova Models Using Multidimensional Chimera Simulations, James Austin Harris

Doctoral Dissertations

Observations of nuclear abundances in core-collapse supernova (CCSN) ejecta, highlighted by γ-ray [gamma-ray] observations of the ⁴⁴Ti [titanium-44] spatial distribution in the nearby supernova remnants Cassiopeia A and SN 1987A, allow nucleosynthesis calculations to place powerful constraints on conditions deep in the interiors of supernovae and their progenitor stars. This ability to probe where direct observations cannot makes such calculations an invaluable tool for understanding the CCSN mechanism. Unfortunately, despite knowing for two decades that supernovae are intrinsically multi-dimensional events, discussions of CCSN nucleosynthesis have been predominantly based on spherically symmetric (1D) models, which employ a contrived energy source …

Insights Into Planetesimal Evolution: Petrological Investigations Of Regolithic Howardites And Carbonaceous Chondrite Impact Melts, Nicole Gabriel Lunning

Doctoral Dissertations

Asteroidal meteorites are the only available geologic samples from the early part of our solar system’s history. These meteorites contain evidence regarding how the earliest protoplanetary bodies formed and evolved. I use petrological and geochemical techniques to investigate the evolution of these early planetesimals, focusing on two meteorite types: Howardites, which are brecciated samples of a differentiated parent body (thought to be the asteroid 4 Vesta), and CV chondrites, which are primitive chondrites that have not undergone differentiation on their parent body.

Quantitative petrological analysis and characterization of paired regolithic (solar wind-rich) howardites indicate that this large sample of the …

On The Existence And Uniqueness Of Static, Spherically Symmetric Stellar Models In General Relativity, Josh Michael Lipsmeyer

Masters Theses

The "Fluid Ball Conjecture" states that a static stellar model is spherically symmetric. This conjecture has been the motivation of much work since first mentioned by Kunzle and Savage in 1980. There have been many partial results( ul-Alam, Lindblom, Beig and Simon,etc) which rely heavily on arguments using the positive mass theorem and the equivalence of conformal flatness and spherical symmetry. The purpose of this paper is to outline the general problem, analyze and compare the key differences in several of the partial results, and give existence and uniqueness proofs for a particular class of equations of state which represents …

Near-Infrared (2 – 4 Micron) Spectroscopy Of Near-Earth Asteroids: A Search For Oh/H2o On Small Planetary Bodies, Nathanael Richard Wigton

Masters Theses

Near-Earth asteroids (NEAs) are not expected to have H₂O [water] ice on their surfaces because a) most accreted dry and therefore never contained H₂O, and b) their relatively high surface temperatures should drive rapid H₂O ice sublimation. However, OH/H₂O has been detected on other anhydrous inner solar system objects, including the Moon and Vesta. Possible sources for OH/H₂O in the inner Solar System might include production via solar wind interactions, carbonaceous chondrite or cometary impact delivery, or native OH/H₂O molecules bound to phyllosilicates. As these processes are active …

Cross Sections Fall 2014/Winter 2015, Department Of Physics And Astronomy

Cross Sections

No abstract provided.

Cross Sections Spring/Summer 2014, Department Of Physics And Astronomy

Cross Sections

No abstract provided.

Graphic Representation Of Exotic Nuclear Shapes In The Pasta Phase Of Matter In Neutron Stars, Mark A. Kaltenborn

Chancellor’s Honors Program Projects

No abstract provided.

Cross Sections Fall 2013/Winter 2014, Department Of Physics And Astronomy

Cross Sections

No abstract provided.

The Study Of Nuclear Structure Of Neutron-Rich 81ge And Its Contribution In The R-Process Via The Neutron Transfer Reaction 80ge(D,P), Sunghoon Ahn

Doctoral Dissertations

The study of low-lying levels of nuclei near closed shells not only elucidates the evolution of nuclear shell structure far from stability, but also affects estimates of heavy element nucleosynthesis in supernova explosions. Especially, the properties of the low-lying levels in ⁸¹Ge[Germanium 81] are important because the sensitivity study of the r-process pointed out that the properties of the nucleus can affect the final bundance pattern. Also, the spins and parities measurements of the states are essential to understand the shape coexistence in odd-mass N = 49 isotones.

This work describes the study of the odd-mass N = …

Statistical Ensemble Analysis For Simulating Extrinsic Noise-Driven Response In Nf-Κb Signaling Networks, Jaewook Joo, Steven J. Plimpton, Jean-Loup Faulon

Physics and Astronomy Publications and Other Works

Background

Gene expression profiles and protein dynamics in single cells have a large cell-to-cell variability due to intracellular noise. Intracellular fluctuations originate from two sources: intrinsic noise due to the probabilistic nature of biochemical reactions and extrinsic noise due to randomized interactions of the cell with other cellular systems or its environment. Presently, there is no systematic parameterization and modeling scheme to simulate cellular response at the single cell level in the presence of extrinsic noise.

Results

In this paper, we propose a novel statistical ensemble method to simulate the distribution of heterogeneous cellular responses in single cells. We capture …

Nature And Degree Of Aqueous Alteration Of Outer Main Belt Asteroids And Cm And Ci Carbonaceous Chondrites, Driss Takir

Doctoral Dissertations

CM (Mighei-like) and CI (Ivuna-like) carbonaceous chondrites are primitive meteorites that consist of some of the most pristine matter known in the Solar System. They are thought to be genetically related to outer Main Belt asteroids (C-, D-, G-, F-, T-, and B-types) that span the 2.5 < a < 4.0 AU region. They are also thought to be the source that might have delivered water and organics to terrestrial planets during their accretion. The goal of this dissertation is to develop reliable 3-µm [micron] spectral indicators that can place constraints on the degree and location of aqueous alteration in the outer Main Belt region, and on the nature of phyllosilicate mineralogy on the surface of these asteroids. To that end, we have undertaken combined petrologic, geochemical, and spectroscopic analyses of CM and CI chondrites and outer Main Belt asteroids. Using the SpeX spectrograph/imager at NASA Infrared Telescope Facility (IRTF), we measured near-infrared (NIR: 0.7-4.0 µm) spectra of 40 outer Main Belt asteroids that allowed the identification of four 3-µm spectral groups, each of which presumably reflects a distinct surface mineralogy. We also measured spectra of 9 CM chondrites (in addition to the CI chondrite Ivuna) in the laboratory under asteroid-like conditions. These measurements revealed three spectral groups of CM chondrites, all of which are distinct from the spectrum of Ivuna on the basis of the 3-μm band center and shape of spectra, showing that distinct parent body aqueous alteration environments experienced by different carbonaceous chondrites can be distinguished using reflectance spectroscopy. All CM and CI chondrites in the present study are found to be similar to the group of asteroids that are located in the 2.5 < a < 3.3 AU region and exhibit a sharp 3-µm feature, attributed to OH-stretching in hydrated minerals. However, no meteorite match was found for asteroids with a rounded 3-µm feature that are located farther from the Sun (3.0 < a < 4.0 AU), or for groups with distinctive spectra like 1 Ceres or 52 Europa.