Astrophysics and Astronomy Commons^™

Supertiger Elemental Abundances For The Charge Range $41 \Leq Z \Leq 56$, Nathan Elliot Walsh

Arts & Sciences Electronic Theses and Dissertations

No abstract provided.

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 …

On The Time Variation Of Dust Extinction And Gas Absorption For Type Ia Supernovae Observed Through A Nonuniform Interstellar Medium, Xiaosheng Huang, G Aldering, M. Biederman, B. Herger

Physics and Astronomy

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures () will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent …

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

Chancellor’s Honors Program Projects

No abstract provided.

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 …

Type Ia Supernova Rate Measurements To Redshift 2.5 From Candels: Searching For Prompt Explosions In The Early Universe, Steven A. Rodney, Adam G. Riess, Louis-Gregory Strolger, Tomas Dahlen, Or Graur, Stefano Casertano, Mark E. Dickinson, Henry C. Ferguson, Peter Garnavich, Brian Hayden, Saurabh W. Jha, David O. Jones, Robert P. Kirshner, Anton M. Koekemoer, Curtis Mccully, Bahram Mobasher, Brandon Patel, Benjamin J. Weiner, S. Bradley Cenko, Kelsey I. Clubb, Michael Cooper, Alexei V. Filippenko, Teddy F. Frederiksen, Jens Hjorth, Bruno Leibundgut, Thomas Matheson, Hooshang Nayyeri, Kyle Penner, Jonathan Trump, Jeffrey M. Silverman, Vivian U, K. Azalee Bostroem, Peter Challis, Abhijith Rajan, Schuyler Wolff, S. M. Faber, Norman A. Grogin, Dale D. Kocevski

Physics and Astronomy Faculty Publications

The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ~0.25 deg² with ~900 HST orbits spread across five fields over three years. . . .

For the remainder of the abstract, please visit:

http://dx.doi.org/10.1088/0004-6256/148/1/13

Lensed Type Ia Supernovae As Probes Of Cluster Mass Models, J Nordin, David Rubin, J Richard, E Rykoff, Greg Aldering, R Amanullah, H Atek, K Barbary, S Deustua, H K. Fakhouri, A S. Fruchter, A Goobar, I Hook, E Y. Hsiao, Xiaosheng Huang, J P. Kneib, C Lidman, J Meyers, S Perlmutter, C Saunders, A L. Spadafora, N Suzuki

Physics and Astronomy

Using three magnified Type Ia supernovae (SNe Ia) detected behind CLASH (Cluster Lensing and Supernovae with Hubble) clusters, we perform a first pilot study to see whether standardizable candles can be used to calibrate cluster mass maps created from strong lensing observations. Such calibrations will be crucial when next-generation Hubble Space Telescope cluster surveys (e.g. Frontier) provide magnification maps that will, in turn, form the basis for the exploration of the high-redshift Universe. We classify SNe using combined photometric and spectroscopic observations, finding two of the three to be clearly of Type Ia and the third probable. The SNe exhibit …

Detecting The Rapidly Expanding Outer Shell Of The Crab Nebula: Where To Look, Xiang Wang, Gary J. Ferland, J. A. Baldwin, E. D. Loh, C. T. Richardson

Physics and Astronomy Faculty Publications

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emissions from high ionization lines that will not be emitted by the Crab's filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The near-NIR [Ne VI] λ7.652 μ …

The Nature Of The H2-Emitting Gas In The Crab Nebula, C. T. Richardson, J. A. Baldwin, Gary J. Ferland, E. D. Loh, C. A. Kuehn, A. C. Fabian, Philippe Salomé

Physics and Astronomy Faculty Publications

Understanding how molecules and dust might have formed within a rapidly expanding young supernova remnant is important because of the obvious application to vigorous supernova activity at very high redshift. In previous papers, we have mapped the Crab nebula (the Crab) in a rotovibrational H₂emission line, and then measured the molecular excitation temperature for a few of the brighter H₂-emitting knots that we have found to be scattered throughout the Crab's filaments. We found that H₂ emission is often quite strong, correlates with optical low-ionization emission lines and has a surprisingly high excitation temperature. Here, …

The Hubble Space Telescope * Cluster Supernova Survey. Ii. The Type Ia Supernova Rate In High-Redshift Galaxy Clusters, K Barbary, G Aldering, R Amanullah, M Brodwin, N Connolly, Ks Dawson, M Doi, P Eisenhardt, L Faccioli, V Fadeyev, Hk Fakhouri, As Fruchter, D G. Gilbank, Md Gladders, G Goldhaber, A Goobar, T Hattori, E Hsiao, Xiaosheng Huang, Y Ihara, K Kashikawa, B Koester, K Konishi, M Kowalski, C Lidman, L Lubin, J Meyers, T Morokuma, T Oda, N Panagia, S Perlmutter, M Postman, P Ripoche, P Rosati, D Rubin, Dj Schlegel, Al Spadafora, Sa Stanford, M Strovink, N Suzuki, N Takanashi, K Tokita, N Yasuda

Physics and Astronomy

We report a measurement of the Type Ia supernova (SN Ia) rate in galaxy clusters at 0.9 < z < 1.46 from the Hubble Space Telescope Cluster Supernova Survey. This is the first cluster SN Ia rate measurement with detected z > 0.9 SNe. Finding 8 ± 1 cluster SNe Ia, we determine an SN Ia rate of 0.50+0.23 –0.19 (stat) +0.10 –0.09 (sys) h 2 70 SNuB (SNuB ≡ 10–12 SNe L –1 ☉, B yr–1). In units of stellar mass, this translates to 0.36+0.16 –0.13 (stat) +0.07 –0.06 (sys) h 2 70 SNuM (SNuM ≡ 10–12 SNe M –1 ☉ yr–1). This represents a …

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

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 …

A Bright Molecular Core In A Crab Nebula Filament, E. D. Loh, J. A. Baldwin, Gary J. Ferland

Physics and Astronomy Faculty Publications

In a sub-arcsec near-infrared survey of the Crab Nebula using the new Spartan Infrared Camera, we have found several knots with high surface brightness in the H2 2.12 μm line and a very large H₂ 2.12 μm to Brγ ratio. The brightest of these knots has an intensity ratio I(H₂ 2.12 μm)/I(Brγ) = 18 ± 9, which we show sets a lower limit on the ratio of masses in the molecular and recombination (i.e., ionized) zones M _mol/M _rec ≥ 0.9, and a total molecular mass within this single knot M _mol ≥ …

Statistical Time-Dependent Model For The Interstellar Gas, H. Gerola, Menas Kafatos, R. Mccray

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present models for temperature and ionization structure of low, uniform-density (n ~ 0.3 cm^-3) interstellar gas in a galactic disk which is exposed to soft X-rays from supernova outbursts occurring randomly in space and time. The structure was calculated by computing the time record of temperature and ionization at a given point by Monte Carlo simulation. The calculation yields probability distribution functions for ionized fraction x, temperature T, and their various observable moments. These time-dependent models predict a bimodal temperature distribution of the gas with structure in x, T that agrees with various observations. Cold regions in the low-density …