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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
Cosmic Diffuse Neutrino And Gamma-Ray Backgrounds In The Mev Regime, Ilukpitiye Samalka Anandagoda
Cosmic Diffuse Neutrino And Gamma-Ray Backgrounds In The Mev Regime, Ilukpitiye Samalka Anandagoda
All Dissertations
Cosmic Multi-Messenger backgrounds include relic diffuse components created in the early Universe and contributions from individual sources. In this dissertation, I present the work done in Anandagoda (2019); Anandagoda et al. (2020, 2023) where type Ia (SNe Ia) and core-collapse supernovae (CCSNe) contributions to the diffuse neutrino and gamma-ray backgrounds in the MeV regime are studied. These backgrounds are referred to as DSNB and DSGB respectively. Based on this work, the diffuse SN Ia background is ~106 times lower (for electron antineutrinos) than the CCSN background making it negligible. The predicted DSNB electron antineutrino flux at earth in the …
Extending Core-Collapse Supernova Simulations: From The Onset Of Explosion To Shock Breakout, Michael A. Sandoval
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 …
Supertiger Elemental Abundances For The Charge Range $41 \Leq Z \Leq 56$, Nathan Elliot Walsh
Supertiger Elemental Abundances For The Charge Range $41 \Leq Z \Leq 56$, Nathan Elliot Walsh
Arts & Sciences Electronic Theses and Dissertations
No abstract provided.
Harbingers Of Exotic Transients: The Electromagnetic Follow-Up Of Gravitational-Wave Transients & Transient Rates, Deep Chatterjee
Harbingers Of Exotic Transients: The Electromagnetic Follow-Up Of Gravitational-Wave Transients & Transient Rates, Deep Chatterjee
Theses and Dissertations
Gravitational waves (GWs) provide a unique view of the universe. They directly probe the extreme gravity and extreme matter of compact objects like black holes (BHs) and neutron stars (NSs) which is not always possible from traditional electromagnetic (EM) wave astronomy. The cataclysmic coalescence of compact object binaries is one of the loudest individual sources of GWs that can be detected by the Laser Interferometer Gravitational wave Observatory (LIGO) and the Virgo Observatory. If one of the component is a NS, there is a possibility that the merger is bright in the EM spectrum. The relativistic astrophysics could launch a …
Collective Neutrino Flavor Oscillations In Multiple Dimensions And Scales, Joshua D. Martin
Collective Neutrino Flavor Oscillations In Multiple Dimensions And Scales, Joshua D. Martin
Physics & Astronomy ETDs
Hot and dense astrophysical environments such as the early universe, core collapse novae and binary neutron star mergers generate dense neutrino gases which can sub- sequently have an important effect on processes which occur in these environments. In this thesis we will present the results from several numerical simulations of these gases particularly in cases which are relevant to core collapse supernovae. These simulations employ fewer imposed spatial symmetries than those used in earlier works, and provide insight into behavior which may be expected to occur in three key regions of the explosion. We observe that when the neutrino gas …
Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory
Accuracy And Stability Of Integration Methods For Neutrino Transport In Core Collapse Supernovae, Kyle A. Gregory
Chancellor’s Honors Program Projects
No abstract provided.
Time-Dependent Spectropolarimetric Modeling Of Interacting Core Collapse Supernovae, Leah N. Huk
Time-Dependent Spectropolarimetric Modeling Of Interacting Core Collapse Supernovae, Leah N. Huk
Electronic Theses and Dissertations
Explosive deaths of massive stars in core collapse supernovae are rare events that are only observed with any frequency at large intergalactic distances. This makes identification of progenitors difficult and massive star evolution a challenge to pin down. This dissertation addresses the question of how the properties of the circumstellar environment around supernovae can be used to identify progenitors via their mass loss history. Massive stars all lose mass through a variety of mechanisms that are characteristic of their mass, age, and binarity. This gives rise to a wide range of circumstellar environments which with supernovae may interact, producing multi-component …
Emission From Black Holes And Supernovae In The Early Universe, Brandon Kerry Wiggins
Emission From Black Holes And Supernovae In The Early Universe, Brandon Kerry Wiggins
Theses and Dissertations
To constrain the era when the first galaxies and stars appeared upcoming instruments will rely on the brightest events in the universe: supernovae and brilliant emission from massive black holes. In this dissertation, we investigate the observability of certain types of supernovae of the very first stars (Population III stars) and find that while these events are sufficiently luminous to be observed with deep-sky instruments such as the James Webb Space Telescope (JWST), they may not observe these particular types of events in their lifetimes. We next explore the origins of massive black holes and introduce the direct collapse hypothesis …
Neutrino Signatures In Terrestrial Detectors From Two- And Three-Dimensional Core-Collapse Supernovae Simulations, Tanner Brooks Devotie
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. νe, νe, νx and νx) [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) …
A Physically-Based Type Ii Supernova Feedback Model In Sph Simulations, Keita Todoroki
A Physically-Based Type Ii Supernova Feedback Model In Sph Simulations, Keita Todoroki
UNLV Theses, Dissertations, Professional Papers, and Capstones
We implement and test a core-collapse Type II SN feedback that is physically motivated and produces good agreement with observations in galaxy formation simulations. The model includes both kinetic and thermal feedback, allowing wind particles to receive a velocity kick that mimics galactic winds and distributes mass and metallicity to the interstellar and intergalactic medium. We also include a phenomenological stellar feedback to study a possible enhancement of the efficiency of the SN-II feedback by creating lower-density ambient gas medium of the stellar populations by distribution of thermal energy. Our SN-II model is unique in the sense that it computes …
Analysis Of 26Al + P Elastic And Inelastic Scattering Reactions And Galactic Abundances Of 26Al, Stephen Todd Pittman
Analysis Of 26Al + P Elastic And Inelastic Scattering Reactions And Galactic Abundances Of 26Al, Stephen Todd Pittman
Doctoral Dissertations
26Al(p,p)26Al and 26Al(p,p’)26Al* scattering reactions were performed at the Holifield Radioactive Ion Beam Facility (HRIBF) at the Oak Ridge National Laboratory (ORNL). The purpose of the elastic scattering study was to determine properties of previously uncharacterized 27Si levels above the proton threshold in the energy range E(c.m.) ~ 0.5 - 1.5 MeV and to calculate reaction rates for the 26Al(p,γ[gamma])27Si reaction that destroys 26Al. The inelastic scattering reaction was also evaluated to investigate the reaction that produces the metastable state of 26Al at E(c.m.) = 228 keV, …
Towards Simulations Of Binary Neutron Star Mergers And Core-Collapse Supernovae With Genasis, Reuben Donald Budiardja
Towards Simulations Of Binary Neutron Star Mergers And Core-Collapse Supernovae With Genasis, Reuben Donald Budiardja
Doctoral Dissertations
This dissertation describes the current version of GenASiS and reports recent progress in its development. GenASiS is a new computational astrophysics code built for large-scale and multi-dimensional computer simulations of astrophysical phenomena, with primary emphasis on the simulations of neutron star mergers and core-collapse supernovae. Neutron star mergers are of high interest to the astrophysics community because they should be the prodigious source of gravitation waves and the most promising candidates for gravitational wave detection. Neutron star mergers are also thought to be associated with the production of short-duration, hard-spectral gamma-ray bursts, though the mechanism is not well understood. In …