相关论文: Exact axially symmetric galactic dynamos
The irregular polarity reversals of the Earth's magnetic field have attracted much interest during the last decades. Despite the fact that recent numerical simulations of the geodynamo have shown nice polarity transitions, the very reason…
Using a one-dimensional $\alpha\omega$-dynamo model appropriate to galaxies, we study the possibility of dynamo action driven by a stochastic alpha effect and shear. To determine the field evolution, one needs to examine a large number of…
The problem posed by the possible existence/non-existence of spatially non-symmetric kinetic equilibria has remained unsolved in plasma theory. For collisionless magnetized plasmas this involves the construction of stationary solutions of…
Magnetic fields in nearby, star-forming galaxies reveal both large-scale patterns and small-scale structures. A large-scale field reversal may exist in the Milky Way but no such reversals have been observed so far in external galaxies. The…
Axially symmetric spacetimes play an important role in the relativistic description of rotating astrophysical objects like black holes, stars, etc. In gravitational theories that venture beyond the usual Riemannian geometry by allowing…
A dynamo model is presented, based on a previously introduced kinematic model, in which the reaction of the magnetic field on the mass flow through the Lorentz force is included. Given the base mass flow corresponding to the case with no…
Cosmic kinematic fast dynamo is found in non-inflationary phases of an ellipsoidal anisotropic cosmological metric background solution of Einstein field equations of general relativity. The magnetic field is amplified inside the universe…
We define a discrete gauge-invariant Yang-Mills-Higgs action on spacetime simplicial meshes. The formulation is a generalization of classical lattice gauge theory, and we prove consistency of the action in the sense of approximation theory.…
We report results for the alignments of galaxies in the EAGLE and cosmo-OWLS simulations as a function of galaxy separation and halo mass. The combination of these hydro-cosmological simulations enables us to span four orders of magnitude…
Exchange symmetry in acceleration partitions the configuration space of an N particle, one-dimensional, gravitational system into N! equivalent cells. We take advantage of the resulting small angular extent of each cell to construct a…
The possibility of generating a magnetic field by dynamo effect with anisotropic electrical conductivity rather than turbulent flow has been demonstrated theoretically (Plunian & Alboussi\`ere 2020) and experimentally (Alboussi\`ere et al.…
The kinematics of the stellar halo hold important clues to the assembly history and mass distribution of the Galaxy. In this study, we map the kinematics of stars across the Galactic halo with the H3 Survey. We find a complex distribution…
An exact solution of the Einstein-Maxwell field equations for a conformastationary metric with magnetized disk-haloes sources is worked out in full. The characterization of the nature of the energy momentum tensor of the source is…
A general procedure to find static and axially symmetric, interior solutions to the Einstein equations is presented. All the so obtained solutions, verify the energy conditions for a wide range of values of the parameters, and match…
Axially symmetric processes on spheres, for which the second-order dependency structure may substantially vary with shifts in latitude, are a prominent alternative to model the spatial uncertainty of natural variables located over large…
For specifically coupled values of the quadratic gravity parameters, we present a fully explicit static spherically symmetric solution. It contains the central singularity surrounded by the black-hole or the cosmological horizon for the…
The magnetic field outside the earth is in good approximation a harmonic vector field determined by its values at the earth's surface. The direction problem seeks to determine harmonic vector fields vanishing at infinity and with prescribed…
Observations of dwarf galaxies suggest the presence of large-scale magnetic fields. However the size and slow rotation of these galaxies appear insufficient to support a mean-field dynamo action to excite such fields. Here we suggest a new…
Bogomol'nyi-Prasad-Sommerfield solitons in models with spontaneously broken gauge symmetry have been intensively studied at infinite gauge coupling limit, where the governing equation -- so-called master equation -- is exactly solvable.…
Choosing a simple class of flows, with characteristics that may be present in the Earth's core, we study the ability to generate a magnetic field when the flow is permitted to oscillate periodically in time. The flow characteristics are…