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Besides expanding anisotropically, the universe can also be anisotropic at the level of its (spatial) curvature. In particular, models with anisotropic curvature and isotropic expansion leads both to a $\Lambda$CDM-like phenomenology and to…

广义相对论与量子宇宙学 · 物理学 2017-11-17 Felipe O. Franco , Thiago S. Pereira

We present a new magnetohydrodynamic (MHD) simulation code with the aim of providing accurate numerical solutions to astrophysical phenomena where discontinuities, shock waves, and turbulence are inherently important. The code implements…

We present the formalism for the covariant treatment of gravitational radiation in a magnetized environment and discuss the implications of the field for gravity waves in the cosmological context. Our geometrical approach brings to the fore…

广义相对论与量子宇宙学 · 物理学 2014-11-17 Christos G. Tsagas

A quantum field model of helical MHD stochastically forced by gaussian hydrodynamic, magnetic and mixed noices is investigated. These helical noises lead to an exponential increase of magnetic fluctuations in the large scale range.…

混沌动力学 · 物理学 2007-05-23 M. Hnatic , M. Jurcisin , M. Stehlik

Non-axisymmetric, flow-driven instabilities in the incompressible Hall-MHD model are studied in a differentially rotating cylindrical plasma. It is found that in the Hall-MHD regime, both whistler waves and ion-cyclotron waves can extract…

等离子体物理 · 物理学 2026-04-16 Alexandre Sainterme , Fatima Ebrahimi

Based on a new approach on modeling the magnetically dominated outflows from AGNs (Li et al. 2006), we study the propagation of magnetic tower jets in gravitationally stratified atmospheres (such as a galaxy cluster environment) in large…

天体物理学 · 物理学 2008-11-26 Masanori Nakamura , Hui Li , Shengtai Li

We propose a cosmological model that describes isotropic expansion of inhomogeneous universe. The energy-momentum tensor that creates the spatial inhomogeneity may not affect the uniform expansion scaling factor $a(t)$ in the FLRW-like…

高能物理 - 理论 · 物理学 2014-10-15 Wei-Jian Geng , H. Lu

We make precise the heretofore ambiguous statement that anisotropic stress is a sign of a modification of gravity. We show that in cosmological solutions of very general classes of models extending gravity --- all scalar-tensor theories…

宇宙学与河外天体物理 · 物理学 2014-11-11 Ippocratis D. Saltas , Ignacy Sawicki , Luca Amendola , Martin Kunz

Polarisation measurements by the Event Horizon Telescope from M87$^{\ast}$ and Sgr A$^\ast$ suggest that there is a dynamically strong, ordered magnetic field, typical of what is expected of a magnetically arrested accretion disk (MAD). In…

高能天体物理现象 · 物理学 2024-07-29 León Salas , Gibwa Musoke , Koushik Chatterjee , Sera Markoff , Oliver Porth , Matthew Liska , Bart Ripperda

Comprehending the manner in which magnetic fields affect propagating waves is a first step toward constructing accurate helioseismic models of active region sub-surface structure and dynamics. Here, we present a numerical method to compute…

天体物理学 · 物理学 2009-11-13 Shravan M. Hanasoge

Compressible turbulence, especially the magnetized version of it, traditionally has a bad reputation with researchers. However, recent progress in theoretical understanding of incompressible MHD as well as that in computational capabilities…

天体物理学 · 物理学 2007-05-23 Jungyeon Cho , A. Lazarian

The standing quasi modes in a cylindrical incompressible flux tube with magnetic twist that undergoes a radial density structuring is considered in ideal magnetohydrodynamics (MHD). The radial structuring is assumed to be a linearly varying…

太阳与恒星天体物理 · 物理学 2011-05-06 K. Karami , K. Bahari

We present initial results from the first 3-dimensional numerical magnetohydrodynamical (MHD) simulations of magnetic field evolution in merging clusters of galaxies. Within the framework of idealized initial conditions similar to our…

天体物理学 · 物理学 2009-10-31 K. Roettiger , J. M. Stone , J. O. Burns

We suggest a new approach that could be used for modeling both the large scale behavior of astrophysical jets and the magnetically dominated explosions in astrophysics. We describe a method for modeling the injection of magnetic fields and…

天体物理学 · 物理学 2009-11-11 Hui Li

Extended magnetohydrodynamics (XMHD) is a fluid plasma model generalizing ideal MHD by taking into account the impact of Hall drift effects and the influence of electron inertial effects. XMHD has a Hamiltonian structure which has received…

偏微分方程分析 · 数学 2024-06-26 Christophe Cheverry , Nicolas Besse

Recent observations of reflected propagating and standing slow-mode waves in hot flaring coronal loops have spurred our investigation into their underlying excitation and damping mechanisms. To understand these processes, we conduct 2.5D…

太阳与恒星天体物理 · 物理学 2024-04-01 Tongjiang Wang , Leon Ofman , Stephen J. Bradshaw

We conduct global galactic--scale magnetohydrodynamical (MHD) simulations of the cosmic--ray driven dynamo. We assume that exploding stars deposit small--scale, randomly oriented, dipolar magnetic fields into the differentially rotating…

星系天体物理 · 物理学 2009-11-13 Michał Hanasz , Dominik Wóltański , Kacper Kowalik , Rafał Pawłaszek

Unconfined relativistic outflows from rotating, magnetized compact objects are often well-modeled by assuming the field geometry is approximately a split-monopole at large radii. Earlier work has indicated that such an unconfined flow has…

高能天体物理现象 · 物理学 2009-11-29 Alexander Tchekhovskoy , Jonathan C. McKinney , Ramesh Narayan

We perform two-dimensional relativistic magnetohydrodynamic simulations of a mildly relativistic shock propagating through an inhomogeneous medium. We show that the postshock region becomes turbulent owing to preshock density inhomogeneity,…

高能天体物理现象 · 物理学 2015-05-20 Yosuke Mizuno , Martin Pohl , Jacek Niemiec , Bing Zhang , Ken-Ichi Nishikawa , Philip E. Hardee

Optical modes in anisotropic slab waveguides with topological and chiral magnetoelectric effects are investigated analytically, by deriving the closed-form characteristic equations of the modes and hence computing the dispersion-diagrams.…

光学 · 物理学 2016-05-04 Nahid Talebi