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The Universe at present is highly magnetized, with fields of the order of a few 10^-5 G and coherence lengths larger than 10 kpc in typical galaxies like the Milky Way. We propose that the magnetic field was amplified to this values already…

星系天体物理 · 物理学 2015-06-17 Jennifer Schober , Dominik R. G. Schleicher , Ralf S. Klessen

We study the evolution of an inflation-generated magnetic field, due to its coupling to fluid motions, during cosmological phase transitions. We find that the magnetic field stays almost unchanged on large scales, while on small scales the…

宇宙学与河外天体物理 · 物理学 2013-05-30 Tina Kahniashvili , Axel Brandenburg , Leonardo Campanelli , Bharat Ratra , Alexander G. Tevzadze

We study the evolution of galactic magnetic fields using 3D smoothed particle magnetohydrodynamics (SPMHD) simulations of galaxies with an imposed spiral potential. We consider the appearance of reversals of the field, and amplification of…

星系天体物理 · 物理学 2016-09-07 C. L. Dobbs , D. J. Price , A. R. Pettitt , M. R. Bate , T. Tricco

We have measured the Faraday rotation toward a large sample of polarized radio sources behind the Large Magellanic Cloud (LMC), to determine the structure of this galaxy's magnetic field. The magnetic field of the LMC consists of a coherent…

We show that a large-scale, weak magnetic field threading a turbulent accretion disk tends to be advected inward, contrary to previous suggestions that it will be stopped by outward diffusion. The efficient inward transport is a consequence…

天体物理学 · 物理学 2009-11-13 David M. Rothstein , Richard V. E. Lovelace

It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the…

天体物理学 · 物理学 2007-05-23 Axel Brandenburg , Kandaswamy Subramanian

The effect of magnetic field on the nonlinear growth rate of Rayleigh-Taylor instability induced two fluid interfacial structures has been investigated. The magnetic field is assumed to be parallel to the plane of the two fluid interface…

等离子体物理 · 物理学 2015-05-27 M. R. Gupta , Labakanta Mandal , Sourav Roy , Manoranjan Khan

Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to the winding up of a primordial cosmological field or due to amplification of a small seed field by a turbulent galactic…

天体物理学 · 物理学 2007-05-23 K. Subramanian

The turbulent diffusion tensor describing the evolution of the mean concentration of a passive scalar is investigated for non-helically forced turbulence in the presence of rotation or a magnetic field. With rotation, the Coriolis force…

太阳与恒星天体物理 · 物理学 2009-05-09 Axel Brandenburg , Andreas Svedin , Geoffrey M. Vasil

New high-resolution observations reveal that small-scale magnetic flux concentrations have a delicate substructure on a spatial scale of 0.1''. Its basic structure can be interpreted in terms of a magnetic flux sheet or tube that vertically…

天体物理学 · 物理学 2007-05-23 Oskar Steiner

We consider primordial spectra with simple power behaviours and show that in the Navier-Stokes and magnetohydrodynamics equations without forcing, there exists systems in three dimensions with a subsequent inverse cascade, transferring…

天体物理学 · 物理学 2009-10-28 P. Olesen

During the common envelope (CE) phase, a giant star in a binary system overflows its Roche lobe and unstable mass transfer leads to a spiral-in of the companion, resulting in a close binary system or in a merger of the stellar cores. Dynamo…

太阳与恒星天体物理 · 物理学 2016-07-21 Sebastian T. Ohlmann , Friedrich K. Roepke , Ruediger Pakmor , Volker Springel , Ewald Mueller

The explanation of the observed galactic magnetic fields may require the existence of a primordial magnetic field. Such a field may arise during the early cosmological phase transitions, or because of other particle physics related…

天体物理学 · 物理学 2009-10-30 Kari Enqvist

We study the pumping of magnetic flux in three-dimensional compressible magnetoconvection in the context of stellar dynamos. The simulation domain represents a rectangular section from the lower part of a stellar convection zone plus the…

天体物理学 · 物理学 2009-11-07 M. Ossendrijver , M. Stix , A. Brandenburg , G. Ruediger

The magnetic fields of spiral galaxies are so strong that they cannot be primordial. Their typical values are over one billion times higher than any value predicted for the early Universe. Explaining this immense growth and incorporating it…

Magnetic fields on the order of 100 $\mu$G observed in young supernova remnants cannot be amplified by shock compression alone. To investigate the amplification caused by turbulent dynamo, we perform three-dimensional MHD simulations of the…

星系天体物理 · 物理学 2022-12-28 Yue Hu , Siyao Xu , James M. Stone , Alex Lazarian

We present a simplified model in which we suggest that two important galactic problems -the magnetic field configuration at large scales and the flat rotation curve- may be simultaneously explained. A highly convective disc produces a high…

天体物理学 · 物理学 2007-05-23 E. Battaner , H. Lesch , E. Florido

We study numerically large-scale magnetic field evolution and its enhancement in gaseous disks of spiral galaxies. We consider a set of models with the various spiral pattern parameters and the initial magnetic field strength with taking…

星系天体物理 · 物理学 2018-01-31 S. A. Khoperskov , S. S. Khrapov

The growth and saturation of magnetic field in conducting turbulent media with large magnetic Prandtl numbers are investigated. This regime is very common in low-density hot astrophysical plasmas. During the early (kinematic) stage, weak…

天体物理学 · 物理学 2009-11-07 A. A. Schekochihin , S. C. Cowley , G. W. Hammett , J. L. Maron , J. C. McWilliams

Spectropolarimetric observations show that many low-mass stars possess large-scale poloidal magnetic fields with considerable dipole component, which in some cases exhibit temporal dynamics - cycles or reversals. Although it is widely…

太阳与恒星天体物理 · 物理学 2025-07-02 Anna Guseva , Ludovic Petitdemange , Charly Pinçon