Physical Sciences and Mathematics | Open Access Articles

Hubble Tension And Gravitational Self-Interaction, Corey Sargent, William Clark, Alexander Deur, Balša Terzić

Physics Faculty Publications

One of the most important problems vexing the ΛCDM cosmological model is the Hubble tension. It arises from the fact that measurements of the present value of the Hubble parameter performed with low-redshift quantities, e.g. the Type IA supernova, tend to yield larger values than measurements from quantities originating at high-redshift, e.g. fits of cosmic microwave background radiation. It is becoming likely that the discrepancy, currently standing at 5σ, is not due to systematic errors in the measurements. Here we explore whether the self-interaction of gravitational fields in General Relativity, which are traditionally neglected when studying the evolution …

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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 …

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A Mildly Relativistic Outflow From The Energentic, Fast-Rising Blue Optical Transient Css161010 In A Dwarf Galaxy, Deanne L. Coppejans, R. Margutti, G. Terreran, A. J. Nayana, E. R. Coughlin, T. Laskar, K. D. Alexander, M. Bietenholz, D. Caprioli, P. Chandra, M. R. Drout, D. Frederiks, C. Frohmaier, K. H. Hurley, C. S. Kochanek, M. Macleod, A. Meisner, P. E. Nugent, A. Ridnaia, D. J. Sand, D. Svinkin, C. Ward, S. Yang, A. Baldeschi, I. V. Chilingarian, Y. Dong, C. Esquivia, W. Fong, C. Guidorzi, P. Lundqvist, D. Milisavljevic

Physics & Astronomy Faculty Research

We present X-ray and radio observations of the Fast Blue Optical Transient CRTS-CSS161010 J045834−081803 (CSS161010 hereafter) at t = 69–531 days. CSS161010 shows luminous X-ray (L x ~ 5 × 1039 erg s−1) and radio (L ν ~ 1029 erg s−1 Hz−1) emission. The radio emission peaked at ~100 days post-transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blast wave. CSS161010 launched a mildly relativistic outflow with velocity Γβc ≥ 0.55c at ~100 days. This is faster than the non-relativistic AT 2018cow (Γβc ~ 0.1c) and closer to ZTF18abvkwla (Γβc …

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Tev Gamma-Ray Observations Of The Galactic Center Ridge By Veritas, P. T. Reynolds, Et Al

Physical Sciences Publications

The Galactic Center ridge has been observed extensively in the past by both GeV and TeV gamma-ray instruments revealing a wealth of structure, including a diffuse component and the point sources G0.9+0.1 (a composite supernova remnant) and Sgr A* (believed to be associated with the supermassive black hole located at the center of our Galaxy). Previous very high energy (VHE) gamma-ray observations with the H.E.S.S. experiment have also detected an extended TeV gamma-ray component along the Galactic plane in the >300 GeV gamma-ray regime. Here we report on observations of the Galactic Center ridge from 2010 to 2014 by the …

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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 …

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High-Velocity Outflows Without Agn Feedback: Eddington-Limited Star Formation In Compact Massive Galaxies, Aleksandar M. Diamond-Stanic, John Moustakas, Christy A. Tremonti, Alison L. Coil, Ryan C. Hickox

Dartmouth Scholarship

We present the discovery of compact, obscured star formation in galaxies at z ~ 0.6 that exhibit 1000 km s^–1 outflows. Using optical morphologies from the Hubble Space Telescope and infrared photometry from the Wide-field Infrared Survey Explorer, we estimate star formation rate (SFR) surface densities that approach Σ_SFR ≈ 3000 M _☉ yr^–1 kpc^–2, comparable to the Eddington limit from radiation pressure on dust grains. We argue that feedback associated with a compact starburst in the form of radiation pressure from massive stars and ram pressure from supernovae and stellar winds is sufficient …

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The Type Ia Supernova 1998bu In M96 And The Hubble Constant, Saurabh Jha, Peter M. Garnavich, Robert P. Kirshner, Peter Challis, Alicia M. Soderberg, Lucas M. Macri, John P. Huchra, Pauline Barmby, Elizabeth J. Barton, Perry Berlind, Warren R. Brown, Nelson Caldwell, Michael L. Calkins, Sheila J. Kannappan, Daniel M. Koranyi, Michael A. Pahre, Kenneth J. Rines, Krzysztof Z. Stanek, Robert P. Stefanik, Andrew H. Szentgyorgyi, Petri Vaisanen, Zhong Wang, Joseph M. Zajac, Adam G. Riess, Alexei V. Filippenko, Weidong Li, Maryam Modjaz, Richard R. Treffers, Carl W. Hergenrother, Eva K. Grebel, Patrick Seitzer, George H. Jacoby, Priscilla J. Benson, Akbar H. Rizvi '99, Laurence A. Marschall, Jeffrey D. Goldader, Matthew Beasley, William D. Vacca, Bruno Leibundgut, Jason Spyromilio, Brian P. Schmidt, Peter R. Wood

Physics and Astronomy Faculty Publications

We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 1998bu in the Leo I Group galaxy M96 (NGC 3368). The data set consists of 356 photometric measurements and 29 spectra of SN 1998bu between UT 1998 May 11 and July 15. The well-sampled light curve indicates the supernova reached maximum light in B on UT 1998 May 19.3 (JD 2450952.8^0.8) with B\12.22^0.03 and V \11.88^0.02. Application of a revised version of the Multicolor Light Curve Shape (MLCS) method yields an extinction toward the supernova of AV\0.94^0.15 mag, and indicates the supernova was of average luminosity compared …

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Full-Text Articles in Physical Sciences and Mathematics

Hubble Tension And Gravitational Self-Interaction, Corey Sargent, William Clark, Alexander Deur, Balša Terzić

Physics Faculty Publications

Cosmic Diffuse Neutrino And Gamma-Ray Backgrounds In The Mev Regime, Ilukpitiye Samalka Anandagoda

All Dissertations

Physics & Astronomy Faculty Research

Tev Gamma-Ray Observations Of The Galactic Center Ridge By Veritas, P. T. Reynolds, Et Al

Physical Sciences Publications

A Physically-Based Type Ii Supernova Feedback Model In Sph Simulations, Keita Todoroki

UNLV Theses, Dissertations, Professional Papers, and Capstones

High-Velocity Outflows Without Agn Feedback: Eddington-Limited Star Formation In Compact Massive Galaxies, Aleksandar M. Diamond-Stanic, John Moustakas, Christy A. Tremonti, Alison L. Coil, Ryan C. Hickox

Dartmouth Scholarship

Physics and Astronomy Faculty Publications