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Astrophysics and Astronomy

Dartmouth College

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Full-Text Articles in Physics

Long-Lived Time-Dependent Remnants During Cosmological Symmetry Breaking: From Inflation To The Electroweak Scale, Marcelo Gleiser, Noah Graham, Nikitas Stamatopoulos Aug 2010

Long-Lived Time-Dependent Remnants During Cosmological Symmetry Breaking: From Inflation To The Electroweak Scale, Marcelo Gleiser, Noah Graham, Nikitas Stamatopoulos

Dartmouth Scholarship

Through a detailed numerical investigation in three spatial dimensions, we demonstrate that long-lived time-dependent field configurations emerge dynamically during symmetry breaking in an expanding de Sitter spacetime. We investigate two situations: a single scalar field with a double-well potential and an SU(2) non-Abelian Higgs model. For the single scalar, we show that large-amplitude oscillon configurations emerge spontaneously and persist to contribute about 1.2% of the energy density of the Universe. We also show that for a range of parameters, oscillon lifetimes are enhanced by the expansion and that this effect is a result of parametric resonance. For the SU(2) case, …


Self‐Consistent Diffusive Lifetimes Of Weibel Magnetic Fields In Gamma‐Ray Bursts, C. H. Jaroschek, H. Lesch, R. A. Treumann Dec 2004

Self‐Consistent Diffusive Lifetimes Of Weibel Magnetic Fields In Gamma‐Ray Bursts, C. H. Jaroschek, H. Lesch, R. A. Treumann

Dartmouth Scholarship

Weibel filamentation in relativistic plasma shell collisions has been demonstrated as an efficient and fast mechanism for the generation of near-equipartition magnetic fields in self-consistent particle-in-cell (PIC) simulations. In generic γ-ray burst (GRB) models with kinetically dominated plasma outflow, sufficient strength and lifetime of magnetic fields are essential to validate synchrotron emission as the source of radiative outbursts. In this article we report on self-consistent PIC simulations of pair-plasma shell collisions in the highly relativistic regime with particle ensembles up to 5 × 108. Energy dependence of magnetic field generation in the Weibel process is discussed, and for …