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With ENZO simulations run on the J\"ulich supercomputers, we have investigated the evolution of magnetic fields in the largest cosmic structures (namely galaxy clusters and filaments connecting them) with unprecedented dynamical range.…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-26 Denis Wittor , Paola Domínguez-Fernández , Franco Vazza , Marcus Brüggen

The ohmic decay of magnetic fields in the crusts of neutron stars is generally believed to be governed by Hall drift which leads to what is known as a Hall cascade. Here we show that helical and fractionally helical magnetic fields undergo…

High Energy Astrophysical Phenomena · Physics 2020-09-18 Axel Brandenburg

Recent (Bose \& Durbin, \textit{Phys. Rev. Fluids}, 1, 073602, 2016) direct numerical simulations (DNS) of adverse- and zero-pressure-gradient boundary layers beneath moderate levels of free stream turbulence ($Tu$ $\le 2\%$) revealed a…

Fluid Dynamics · Physics 2023-09-06 Rikhi Bose , Paul A. Durbin

Bulk high-temperature superconductors (HTS) are capable of generating very strong magnetic fields while maintaining a relatively compact form factor. Solenoids constructed using stacks of ring-shaped bulk HTS have been demonstrated to be…

Applied Physics · Physics 2024-02-16 Dian Weerakonda , Benjamin Bryant , Anthony Dennis , Tobia Nava , John Durrell

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…

Solar and Stellar Astrophysics · Physics 2025-07-02 Anna Guseva , Ludovic Petitdemange , Charly Pinçon

We study the inflationary generation of helical cosmological magnetic fields in a higher-dimensional generalization of the electromagnetic theory. For this purpose, we also include a parity breaking piece to the electromagnetic action. The…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Kumar Atmjeet , T. R. Seshadri , Kandaswamy Subramanian

The mechanism by which the Earth's magnetic field is generated is thought to be thermal convection in the metallic liquid iron core. Computational considerations previously restricted most numerical simulations to a regime where the…

Geophysics · Physics 2017-01-17 Andrey Sheyko , Christopher Finlay , Jean Favre , Andrew Jackson

In our conventional understanding, large-scale magnetic fields are thought to originate from an inverse cascade in the presence of magnetic helicity, differential rotation, or a magneto-rotational instability. However, as recent simulations…

Plasma Physics · Physics 2017-09-20 Kiwan Park

We study the dynamo instability driven by a turbulent two dimensional flow with three components of the form (u(x, y, t), v(x, y, t), w(x, y, t)) sometimes referred to as a 2.5 dimensional flow. This type of flows provides an approximation…

Fluid Dynamics · Physics 2016-08-24 K. Seshasayanan , A. Alexakis

We discuss a model which can generate scale-invariant helical magnetic fields on large scales ($\lesssim 1$Mpc) in the primordial universe. It is also shown that the electric conductivity becomes significant and terminates magnetogenesis…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-11 Tomohiro Fujita , Ruth Durrer

Magnetohydrodynamic (MHD) turbulence is of key importance in many high-energy astrophysical systems, where MHD instabilities can amplify local magnetic field over very short time scales. Specifically, the magnetorotational instability (MRI)…

High Energy Astrophysical Phenomena · Physics 2018-03-30 Philipp Mösta , Christian D. Ott , David Radice , Luke F. Roberts , Erik Schnetter , Roland Haas

Renormalized viscosity, renormalized resistivity, and various energy fluxes are calculated for helical magnetohydrodynamics using perturbative field theory. The calculation is to first-order in perturbation. Kinetic and magnetic helicities…

Chaotic Dynamics · Physics 2008-11-26 Mahendra K. Verma

Observations of galaxy clusters show that the intracluster medium (ICM) is likely to be turbulent and is certainly magnetized. The properties of this magnetized turbulence are determined both by fundamental nonlinear magnetohydrodynamic…

Astrophysics · Physics 2008-11-26 A. A. Schekochihin , S. C. Cowley

(1)The previous theoretical studies showed that in the presence of the small-scale dynamo the large-scale vorticity can produce the the divergent-type helicity flux breaking the equatorial reflection symmetry of the magnetic fluctuations in…

Solar and Stellar Astrophysics · Physics 2026-01-13 V. V. Pipin

Magnetic buoyancy is believed to drive the transport of magnetic flux tubes from the convection zone to the surface of the Sun. The magnetic fields form twisted loop-like structures in the solar atmosphere. In this paper we use helical…

Solar and Stellar Astrophysics · Physics 2011-09-28 Jörn Warnecke , Axel Brandenburg

The amplification of magnetic fields in a highly conducting fluid is studied numerically. During growth, the magnetic field is spatially intermittent: it does not uniformly fill the volume, but is concentrated in long thin folded…

Chaotic Dynamics · Physics 2009-11-10 A. A. Schekochihin , S. C. Cowley , J. L. Maron , J. C. McWilliams

The amplification of magnetic fields is crucial for understanding the observed magnetization of stars and galaxies. Turbulent dynamo is the primary mechanism responsible for that but the understanding of its action in a collapsing…

Astrophysics of Galaxies · Physics 2026-04-22 Muhammed Irshad P , Pallavi Bhat , Kandaswamy Subramanian , Anvar Shukurov

Magnetic fields in galaxies are believed to be the result of dynamo amplification of initially weak seed fields, reaching equipartition strength inside the interstellar medium. The small-scale dynamo appears to be a viable mechanism to…

Astrophysics of Galaxies · Physics 2017-08-16 Michael Rieder , Romain Teyssier

The amplification of primordial magnetic fields via a small-scale turbulent dynamo during structure formation might be able to explain the observed magnetic fields in galaxy clusters. The magnetisation of more tenuous large-scale structures…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 F. Vazza , M. Brüggen , C. Gheller , P. Wang

We present an MHD shell model suitable for computation of various energy fluxes of magnetohydrodynamic turbulence for very small and very large magnetic Prandtl numbers $\mathrm{Pm}$; such computations are inaccessible to direct numerical…

Fluid Dynamics · Physics 2016-09-21 Mahendra K. Verma , Rohit Kumar