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Quantized fields (e.g., the graviton itself) in de Sitter (dS) spacetime lead to particle production: specifically, we consider a thermal spectrum resulting from the dS (horizon) temperature. The energy required to excite these particles…

High Energy Physics - Theory · Physics 2015-05-20 Chiu Man Ho , Stephen D. H. Hsu

The gravitational wave solutions obtained from a perturbation about conformally flat backgrounds in Einstein gravity are investigated. A perturbation theory analysis of the Lesame, Ellis and Dunsby results, based on a covariant approach,…

Astrophysics · Physics 2008-02-03 J. W. Moffat

We use a series of idealized, numerical SPH simulations to study the formation and evolution of galactic, gas-rich disks forming from gas infall within dark matter halos. The temperature and density structure of the gas is varied in order…

Astrophysics of Galaxies · Physics 2015-05-19 Michael Aumer , Andreas Burkert , Peter H. Johansson , Reinhard Genzel

Topological structure has been extensively studied and confirmed in highly correlated condensed matter physics. We explore the gravitational waves emitted from binary neutron star mergers using the pseudoconformal model for dense nuclear…

Nuclear Theory · Physics 2021-07-07 Wen-Cong Yang , Yong-Liang Ma , Yue-Liang Wu

Astrophysical discs which are sufficiently massive and cool are linearly unstable to the formation of axisymmetric structures. In practice, linearly stable discs of surface density slightly below the threshold needed for this instability…

Earth and Planetary Astrophysics · Physics 2025-01-22 Joshua J. Brown , Gordon I. Ogilvie

We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid based AMR-code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if…

Solar and Stellar Astrophysics · Physics 2017-01-18 Matthias Gritschneder , Stefan Heigl , Andreas Burkert

To examine how non-uniform nature of the Galactic gravity might affect length and time scales of the Parker instability, we took three models of gravity, uniform, linear and realistic ones. To make comparisons of the three gravity models on…

Astrophysics · Physics 2009-10-30 Jongsoo Kim , S. S. Hong

We show that a generic relativistic membrane with in-plane pressure and surface density having the same sign is unstable with respect to a series of warping mode instabilities with high wave numbers. We also examine the criteria of…

General Relativity and Quantum Cosmology · Physics 2023-01-18 Huan Yang , Beatrice Bonga , Zhen Pan

We study the Jeans-type gravitational instability for a self-gravitating medium composed of two species, baryonic (bright) and dark matter particles, using a hybrid quantum-classical fluid approach. Baryonic matter is treated classically,…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-13 Kamel Ourabah

Linear stability analysis of the axisymmetric interface of velocity and density discontinuity in rotating gaseous disk has been performed numerically and analytically. Physical mechanisms leading to development of centrifugal and…

Astrophysics · Physics 2007-05-23 C. M. Bezborodov , V. V. Mustsevoy

We consider quantum particle or Gaussian polymer confinement between two surfaces and in cylinders with sinusoidal undulations. In terms of the variational method, we show that the quantum mechanical wave equations have lower ground state…

Soft Condensed Matter · Physics 2009-10-31 Tomonari Dotera , Yasuo Y. Suzuki

For a long time, gravitational instability in the disk of planetesimals has been suspected to be the main engine responsible for the beginning of dust growth, its advantage being that it provides for rapid growth. Its real importance in…

Astrophysics · Physics 2009-11-10 P. Tanga , S. J. Weidenschilling , P. Michel , D. C. Richardson

In this paper, we analyze the stability of a homogeneous self-gravitating plasma, having a non-zero resistivity. This study provides a generalization of the Jeans paradigm for determining the critical scale above which gravitational…

High Energy Astrophysical Phenomena · Physics 2015-03-19 Daniela Pugliese , Nakia Carlevaro , Massimiliano Lattanzi , Giovanni Montani , Riccardo Benini

We consider non-linear plane gravitational waves as propagating space-time defects, and construct the Burgers vector of the waves. In the context of classical continuum systems, the Burgers vector is a measure of the deformation of the…

General Relativity and Quantum Cosmology · Physics 2021-01-27 F. L. Carneiro , S. C. Ulhoa , J. W. Maluf , J. F. da Rocha-Neto

In this work, we study pancake-shaped Bose-Einstein condensates confined by both a cylindrically symmetric harmonic potential and an optical lattice with equal periodicity in two orthogonal directions. We first identify the spectrum of the…

Pattern Formation and Solitons · Physics 2012-05-30 K. J. H. Law , P. G. Kevrekidis , B. P. Anderson , R. Carretero-Gonzalez , D. J. Frantzeskakis

We report on the results of the first 3D SPH simulation of massive, gravitationally unstable protoplanetary disks with radiative transfer. We adopt a flux-limited diffusion scheme justified by the high opacity of most of the disk. The…

Astrophysics · Physics 2009-11-11 Lucio Mayer , Graeme Lufkin , Thomas Quinn , James Wadsley

It is shown that the entropy of low density monochromatic gravitational waves, waves required for the stabilization of the crystalline structure of vacuum cosmic space, varies with the volume in the same manner as the entropy of an ideal…

The problem of how some disk galaxies avoid forming bars remains unsolved. Many galaxy models having reasonable properties continue to manifest vigorous instabilities that rapidly form strong bars and no widely-accepted idea has yet been…

Astrophysics of Galaxies · Physics 2023-11-30 J A Sellwood , R G Carlberg

We investigate the formation of plasma cavities in unmagnetized relativistic pair shocks and demonstrate that these cavities emerge naturally as a nonlinear consequence of asymmetric Weibel instability. We provide an intuitive physical…

High Energy Astrophysical Phenomena · Physics 2026-01-07 Ivan Demidov , Yuri Lyubarsky , Uri Keshet

We investigate the role of thermal instability, arising from radiative cooling of an optically thin, dusty plasma, by linear stability analysis. The corresponding isobaric stability condition for condensation mode is found to be modified…

Plasma Physics · Physics 2007-05-23 Madhurjya P. Bora