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Interstellar magnetic fields in elliptical galaxies are assumed to have their origin in stellar fields that accompany normal mass loss from an evolving population of old stars. The seed fields are amplified by interstellar turbulence driven…

天体物理学 · 物理学 2009-10-30 William G. Mathews , Fabrizio Brighenti

It is demonstrated that strong magnetic fields are produced from a zero initial magnetic field during the pregalactic era, when galaxies are first forming. Their development proceeds in three phases. In the first phase, weak magnetic fields…

天体物理学 · 物理学 2011-02-11 Russell M. Kulsrud , Renyue Cen , Jeremiah P. Ostriker , Dongsu Ryu

We have determined the physical mechanism responsible for the plasma instabilities, which was first found by Ramani and Laval (1978), associated with anisotropic velocity distributions induced by the temperature gradient in which there are…

天体物理学 · 物理学 2009-11-10 Nobuhiro Okabe , Makoto Hattori

We investigate an efficient mechanism for generating magnetic fields in turbulent, collisionless plasmas. By using fully kinetic, particle-in-cell simulations of an initially non-magnetized plasma, we inspect the genesis of magnetization,…

等离子体物理 · 物理学 2021-12-01 F. Pucci , M. Viviani , F. Valentini , G. Lapenta , W. H. Matthaeus , S. Servidio

We report on a first-principles numerical and theoretical study of plasma dynamo in a fully kinetic framework. By applying an external mechanical force to an initially unmagnetized plasma, we develop a self-consistent treatment of the…

高能天体物理现象 · 物理学 2023-08-07 Muni Zhou , Vladimir Zhdankin , Matthew W. Kunz , Nuno F. Loureiro , Dmitri A. Uzdensky

We present results from three-dimensional particle simulations of collisionless shocks with relativistic counter-streaming ion-electron plasmas. Particles are followed over many skin depths downstream of the shock. Open boundaries allow the…

天体物理学 · 物理学 2009-11-10 J. Trier Frederiksen , C. B. Hededal , T. Haugboelle , A. Nordlund

The formation of non-relativistic collisionless shocks in laboratory with ultrahigh intensity lasers is studied via \emph{ab initio} multi-dimensional particle-in-cell simulations. The microphysics behind shock formation and dissipation,…

等离子体物理 · 物理学 2015-06-04 F. Fiuza , R. A. Fonseca , J. Tonge , W. B. Mori , L. O. Silva

Relativistic shocks are usually thought to occur in violent astrophysical explosions. These collisionless shocks are mediated by a plasma kinetic streaming instability, often loosely referred to as the Weibel instability, which generates…

高能天体物理现象 · 物理学 2014-11-20 Mikhail V. Medvedev

Magnetic fields in our Galaxy and nearby galaxies have been revealed by starlight polarization, polarized emission from dust grains and clouds at millimeter and submillimeter wavelength, the Zeeman effect of spectral lines or maser lines…

星系天体物理 · 物理学 2013-08-06 JinLin Han

Magnetic fields appear to be ubiquitous in astrophysical environments. Their existence in the intracluster medium is established through observations of synchrotron emission and Faraday rotation. On the other hand, the nature of magnetic…

宇宙学与河外天体物理 · 物理学 2015-05-30 Dongsu Ryu , Dominik R. G. Schleicher , Rudolf A. Treumann , Christos G. Tsagas , Lawrence M. Widrow

Magnetic fields are considered to be key components of massive stars, with a far-reaching impact on their evolution and ultimate fate. A magnetic mechanism was suggested for the collimated explosion of massive stars, relevant for…

太阳与恒星天体物理 · 物理学 2024-10-28 Swetlana Hubrig , Markus Schöller , Silva P. Järvinen , Aleksandar Cikota , Michael Abdul-Masih , Ana Escorza , Ilya Ilyin

The origin of the magnetic field in galaxies is an open question in astrophysics. Several mechanisms have been proposed related, in general, with the generation of small seed fields amplified by a dynamo mechanism. In general, these…

天体物理学 · 物理学 2009-10-30 O. D. Miranda , M. Opher , R. Opher

Weibel-type instability can self-generate and amplify magnetic fields in both space and laboratory plasmas with temperature anisotropy. The electron Weibel instability has generally proven more challenging to measure than its ion…

Generation and amplification of magnetic fields in plasmas is a long-standing topic that is of great interest to both plasma and space physics. The electron Weibel instability is a well-known mechanism responsible for self-generating…

The filamentation (Weibel) instability plays a key role in the formation of collisionless shocks which are thought to produce Gamma-Ray-Bursts and High-Energy-Cosmic-Rays in astrophysical environments. While it has been known for long that…

等离子体物理 · 物理学 2015-06-18 Antoine Bret

In thin ($\Delta<$ few $\lambda_i$) collisionless current sheets in a space plasma like the magnetospheric tail or magnetopause current layer, magnetic fields can grow {from thermal fluctuation level by the action of the non-magnetic Weibel…

空间物理 · 物理学 2015-05-13 R. A. Treumann , R. Nakamura , W. Baumjohann

The origin of the substantial magnetic fields that are found in galaxies and on even larger scales, such as in clusters of galaxies, is yet unclear. If the second-order couplings between photons and electrons are considered, then…

天体物理学 · 物理学 2007-05-23 Kiyotomo Ichiki , Keitaro Takahashi , Hiroshi Ohno , Hidekazu Hanayama , Naoshi Sugiyama

Magnetic fields are ubiquitous in the Universe. Extragalactic disks, halos and clusters have consistently been shown, via diffuse radio-synchrotron emission and Faraday rotation measurements, to exhibit magnetic field strengths ranging from…

The origin and growth of magnetic fields in galaxies is still something of an enigma. It is generally assumed that seed fields are amplified over time through the dynamo effect, but there are few constraints on the timescale. It has…

Galaxies are observed to host magnetic fields with a typical total strength of around 15microgauss. A coherent large-scale field constitutes up to a few microgauss of the total, while the rest is built from strong magnetic fluctuations over…

星系天体物理 · 物理学 2024-01-09 Maarit J. Korpi-Lagg , Mordecai-Mark Mac Low , Frederick A. Gent