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There is a reformulation of magnetohydrodynamics in which the fundamental dynamical quantities are the positions and velocities of the lines of magnetic flux in the plasma, which turn out to obey equations of motion very much like ideal…

Astrophysics · Physics 2009-10-31 Mattias Christensson , Mark Hindmarsh

It is shown that the standard cosmological model predicts {\it ab initio} generation of large-scale but very small-amplitude cosmic magnetic fields at the epoch of recombination of the primeval plasma. Matter velocities dominated by…

Astrophysics · Physics 2007-05-23 Craig J. Hogan

Radio quasar sightlines with strong MgII absorption lines display statistically enhanced Faraday Rotation Measures (RM) indicating the presence of additional magneto-active plasma with respect to sightlines free of such absorption. In this…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 M. L. Bernet , F. Miniati , S. J. Lilly

Magnetic fields are ubiquitous in the Universe. Recently, cosmological simulations of galaxies have successfully begun to incorporate magnetic fields and their evolution in galaxies and their haloes. However, so far they have mostly focused…

The origin of large scale magnetic fields in the Universe is widely thought to be from early Universe processes, like inflation or phase transitions. These magnetic fields evolve via magnetohydrodynamic processes until the epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-04 Molly Abramson , Emma Clarke , Tina Kahniashvili , Sayan Mandal , Salome Mtchedlidze , Jennifer Schober

Observational evidence for the existence of cosmic magnetic fields in intergalactic space coherent over Mpc scales is presented. Using an unprecedentedly large sample of Faraday rotation measures of radio sources from the NRAO VLA Sky…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-16 Jounghun Lee , Ue-Li Pen , A. Russell Taylor , Jeroen M. Stil , Caleb Sunstrum

We discuss, using simple analytical models and MHD simulations, the origin and parameters of turbulence and magnetic fields in galaxy clusters. Three physically distinct regimes can be identified in the evolution of cluster turbulence and…

Astrophysics · Physics 2009-11-11 Kandaswamy Subramanian , Anvar Shukurov , Nils Erland L. Haugen

We consider the hypothesis that galactic magnetic fields are primordial. We also discuss the various objections to this hypothesis. We assume that there was a magnetic field present in the galactic plasma before the galaxy formed. After the…

Astrophysics · Physics 2016-08-30 Armando M. Howard , Russell M. Kulsrud

We have performed magnetohydrodynamical simulations to study the amplification of magnetic fields in the precursors of shock waves. Strong magnetic fields are required in the precursors of the strong shocks that occur in supernova remnants.…

High Energy Astrophysical Phenomena · Physics 2015-06-17 M. Bruggen

Perpendicular relativistic ($\gamma_0=10$) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately…

High Energy Astrophysical Phenomena · Physics 2018-04-25 Illya Plotnikov , Anna Grassi , Mickael Grech

Magnetic fields are observed beyond the peripheries of optically detected galactic discs, while numerical models of their origin and the typical magnitudes are still absent. Previously, studies of galactic dynamo have avoided considering…

Astrophysics of Galaxies · Physics 2014-09-05 E. Mikhailov , A. Kasparova , D. Moss , R. Beck , D. Sokoloff , A. Zasov

Observations suggest a slower stellar rotation relative to gas rotation in the outer part of the Milky Way Galaxy. This difference could be attributed to an interaction with the interstellar magnetic field. In a simple model, fields of…

Astrophysics of Galaxies · Physics 2016-12-21 Joanna Jałocha , Łukasz Bratek , Jan Pękala , Szymon Sikora , Marek Kutschera

The sunspot penumbra is a transition zone between the strong vertical magnetic field area (sunspot umbra) and the quiet Sun. The penumbra has a fine filamentary structure that is characterized by magnetic field lines inclined toward the…

Solar and Stellar Astrophysics · Physics 2010-12-02 I. N. Kitiashvili , A. G. Kosovichev , N. N. Mansour , A. A. Wray

There are indications that the magnetic field evolution in galaxies might be massively shaped by tidal interactions and mergers between galaxies. The details of the connection between the evolution of magnetic fields and that of their host…

Astrophysics of Galaxies · Physics 2022-03-15 Simon Selg , Wolfram Schmidt

Spiral galaxies host dynamically important magnetic fields which can affect gas flows in the disks and halos. Total magnetic fields in spiral galaxies are strongest (up to 30 \muG) in the spiral arms where they are mostly turbulent or…

Astrophysics · Physics 2009-06-23 Rainer Beck

We perform a study of fluid motions and its temporal evolution in and around a small bipolar emerging flux region using observations made by the Helioseismic and Magnetic Imager (HMI) on-board the Solar Dynamics Observatory (SDO). We employ…

Solar and Stellar Astrophysics · Physics 2020-06-03 C. R. Sangeetha , Durgesh Tripathi , S. P. Rajaguru

We carried out global three-dimensional resistive magnetohydrodynamic simulations of galactic gaseous disks to investigate how the galactic magnetic fields are amplified and maintained. We adopt a steady axisymmetric gravitational potential…

Astrophysics · Physics 2009-11-11 Hiromitsu Nishikori , Mami Machida , Ryoji Matsumoto

The Milky Way is one of the very few spiral galaxies known to host large-scale magnetic field reversals. The existence of the field reversal in the first Galactic quadrant near the Sagittarius spiral arm has been well established, yet…

Astrophysics of Galaxies · Physics 2020-07-29 Yik Ki Ma , S. A. Mao , A. Ordog , J. C. Brown

The shape and the dynamics of reversals of the magnetic field in a turbulent dynamo experiment are investigated. We report the evolution of the dipolar and the quadrupolar parts of the magnetic field in the VKS experiment, and show that the…

Fluid Dynamics · Physics 2015-05-20 Christophe Gissinger

The average strength of the total magnetic field in the Milky Way, derived from radio synchrotron data under the energy equipartition assumption, is 6\muG locally and \simeq 10\muG at 3 kpc Galactic radius. Optical and synchrotron…

Astrophysics · Physics 2009-11-10 Rainer Beck