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Magnetic fields are expected to play a key role in the dynamics and the ejection mechanisms that accompany the merger of two neutron stars. General relativistic magnetohydrodynamic (MHD) simulations offer a unique opportunity to unravel the…

General Relativity and Quantum Cosmology · Physics 2022-07-27 C. Palenzuela , R. Aguilera-Miret , F. Carrasco , R. Ciolfi , J. V. Kalinani , W. Kastaun , B. Miñano , D. Viganò

Radio continuum observations allow to reveal the magnetic field structure in the disk and halo of nearby spiral galaxies, their magnetic field strength and vertical scale heights. The spiral galaxies studied so far show a similar magnetic…

Astrophysics of Galaxies · Physics 2014-01-08 Marita Krause

We investigate hydromagnetic turbulence of primordial magnetic fields using magnetohydrodynamics (MHD) in an expanding universe. We present the basic, covariant MHD equations, find solutions for MHD waves in the early universe, and…

Astrophysics · Physics 2014-10-13 Axel Brandenburg , Kari Enqvist , Poul Olesen

Radio observations of galaxy clusters show that there are $\mu$G magnetic fields permeating the intra-cluster medium (ICM), but it is hard to accurately constrain the strength and structure of the magnetic fields without the help of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Hao Xu , Federica Govoni , Matteo Murgia , Hui Li , David C. Collins , Michael L. Norman , Renyue Cen , Luigina Feretti , Gabriele Giovannini

Magnetic fields are an important ingredient of the interstellar medium (ISM). Besides their importance for star formation, they govern the transport of cosmic rays, relevant to the launch and regulation of galactic outflows and winds, which…

One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate from a volume several hundred pc…

Astrophysics of Galaxies · Physics 2015-05-13 Hua-bai Li , C. Darren Dowell , Alyssa Goodman , Roger Hildebrand , Giles Novak

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,…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Yosuke Mizuno , Martin Pohl , Jacek Niemiec , Bing Zhang , Ken-Ichi Nishikawa , Philip E. Hardee

Fluctuation dynamos provide a robust mechanism for amplifying weak seed magnetic fields in turbulent astrophysical plasmas. However, their behaviour in the highly compressible regimes characteristic of the interstellar medium remains…

Astrophysics of Galaxies · Physics 2026-02-18 Ameya Uday Nagdeo , Sharanya Sur , Bhargav Vaidya

Using second-order gauge-invariant perturbation theory, a self-consistent framework describing the non-linear coupling between gravitational waves and a large-scale homogeneous magnetic field is presented. It is shown how this coupling may…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Gerold Betschart , Caroline Zunckel , Peter Dunsby , Mattias Marklund

Via amplification by turbulent dynamo, magnetic fields can be potentially important for the formation of the first stars. To examine the dynamo behavior during the gravitational collapse of primordial gas, we extend the theory of nonlinear…

Solar and Stellar Astrophysics · Physics 2020-08-26 Siyao Xu , Alex Lazarian

Some common properties of helical magnetic fields in decaying and driven turbulence are discussed. These include mainly the inverse cascade that produces fields on progressively larger scales. Magnetic helicity also restricts the evolution…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

We perform ideal MHD high resolution AMR simulations with driven turbulence and self-gravity and find that long filamentary molecular clouds are formed at the converging locations of large-scale turbulence flows and the filaments are…

Astrophysics of Galaxies · Physics 2019-04-10 Pak Shing Li , Richard I. Klein

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…

Astrophysics of Galaxies · Physics 2022-12-28 Yue Hu , Siyao Xu , James M. Stone , Alex Lazarian

Radio observations have revealed magnetic fields in the intracluster medium (ICM) of galaxy clusters nearly in equipartition with turbulence. This suggests magnetic field amplification by dynamo processes. However, observations are limited…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-30 Yoan Rappaz , Jennifer Schober , Abhijit Bhausaheb Bendre , Amit Seta , Christoph Federrath

We show that the relatively strong magnetic fields ($\ge 1 \mu$G) in high redshift objects can be explained by the combined action of an evolving protogalactic fluctuation and electrodynamic processes providing the magnetic seed fields.…

Astrophysics · Physics 2007-05-23 Harald Lesch , Masashi Chiba

We point out that the lower bound on the primordial magnetic field required to seed the galactic dynamo is significantly relaxed in an open universe or in a universe with a positive cosmological constant. It is shown that, for reasonable…

Astrophysics · Physics 2008-11-26 Anne-Christine Davis , Matthew Lilley , Ola Tornkvist

We report results of 3D MHD simulations of the dynamics of buoyant bubbles in magnetized galaxy cluster media. The simulations are three dimensional extensions of two dimensional calculations reported by Jones & De Young (2005). Initially…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 S. M. O'Neill , D. S. De Young , T. W. Jones

Inflation has long been thought as the best way of producing primordial large-scale magnetic fields. To achieve fields strong enough to seed the galactic dynamo, most of the mechanisms operate outside conventional electromagnetic theory.…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-09 Christos G. Tsagas

Spiral galaxies, including the Milky Way, have large-scale magnetic fields with significant energy densities. The dominant theory attributes these magnetic fields to a large-scale dynamo. We review the current status of dynamo theory and…

Astrophysics of Galaxies · Physics 2023-08-31 Axel Brandenburg , Evangelia Ntormousi

Observations of quasars at $\rm z> 6$ report the existence of a billion solar mass black holes. Comprehending their formation in such a short time scale is a matter of ongoing research. One of the most promising scenarios to assemble…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 M. A. Latif , D. R. G. Schleicher , W. Schmidt