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Both observations and modelling of magnetic fields in the diffuse interstellar gas of spiral galaxies are well developed but the theory has been confronted with observations for only a handful of individual galaxies. There is now sufficient…

Astrophysics of Galaxies · Physics 2015-06-23 Cameron Van Eck , Jo-Anne Brown , Anvar Shukurov , Andrew Fletcher

To characterize the possible magnetic structures created on magnetic multilayers a model has been formulated and studied. The interlayer inhomogeneous structures found indicate either (i) a regular periodic, (ii) a quasiperiodic change in…

Materials Science · Physics 2009-10-31 F. V. Kusmartsev , H. S. Dhillon , M. D. Crapper

Dynamo action owing to helically forced turbulence and large-scale shear is studied using direct numerical simulations. The resulting magnetic field displays propagating wave-like behavior. This behavior can be modelled in terms of an…

Astrophysics · Physics 2011-02-11 P. J. Käpylä , A. Brandenburg

We have developed 3D, compressible, non-linear radiative MHD simulations to study the influence of the magnetic field of various strength and geometry on the turbulent convective cells and on the excitation mechanisms of the acoustic…

Solar and Stellar Astrophysics · Physics 2009-01-29 Irina Kitiashvili , Laetitia Jacoutot , Alexander Kosovichev , Alan Wray , Nagi Mansour

Kinetic helicity is a fundamental characteristics of astrophysical turbulent flows. It is not only responsible for the generation of large-scale magnetic fields in the Sun, stars, and spiral galaxies, but it also affects turbulent diffusion…

Fluid Dynamics · Physics 2025-05-15 Igor Rogachevskii , Nathan Kleeorin , Axel Brandenburg

The origin of magnetic fields in the Universe is an open problem. Seed magnetic fields possibly produced in early times may have survived up to the present day close to their original form, providing an untapped window to the primeval…

High Energy Astrophysical Phenomena · Physics 2021-07-01 A. Saveliev , R. Alves Batista

Magnetic fields are a defining yet enigmatic aspect of the interstellar medium (ISM), with their three-dimensional mapping posing a substantial challenge. In this study, we harness the innovative Velocity Gradient Technique (VGT),…

Astrophysics of Galaxies · Physics 2024-01-15 Tyler Schmaltz , Yue Hu , A. Lazarian

An enhancement in high-frequency acoustic power is commonly observed in the solar photosphere and chromosphere surrounding magnetic active regions. We perform 3D linear forward wave modelling with a simple wavelet pulse acoustic source to…

Solar and Stellar Astrophysics · Physics 2015-06-23 Carlos Rijs , Hamed Moradi , Damien Przybylski , Paul S. Cally

The use of acoustic holography in the high-frequency $p$-mode spectrum can resolve the source distributions of enhanced acoustic emissions within halo structures surrounding active regions. In doing so, statistical methods can then be…

Solar and Stellar Astrophysics · Physics 2015-08-06 Chris S. Hanson , Alina C. Donea , K. D. Leka

We introduce and apply a new approach to probe the response of galactic stellar haloes to the interplay between cosmological merger histories and galaxy formation physics. We perform dark matter-only, zoomed simulations of two Milky…

Astrophysics of Galaxies · Physics 2022-01-21 Martin P. Rey , Tjitske K. Starkenburg

Motivated by a scenario of magnetogenesis in which a homogeneous magnetic field is generated during inflation, we study the magnetohydrodynamic evolution of the primordial plasma motions for two kinds of initial conditions -- (i) a…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-28 Axel Brandenburg , Ruth Durrer , Yiwen Huang , Tina Kahniashvili , Sayan Mandal , Shinji Mukohyama

Magnetized plasmas within halos of galaxies leave their footprint on the polarized anisotropies of the cosmic microwave background. The two dominant effects for astrophysical halos are Faraday rotation generating rotation of the plane of…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-16 Nadège Lemarchand , Julien Grain , Guillaume Hurier , Fabien Lacasa , Agnès Ferté

Kinematic dynamo in incompressible isotropic turbulent flows with high magnetic Prandtl number is considered. The approach interpreting an arbitrary magnetic field distribution as a superposition of localized perturbations (blobs) is…

Fluid Dynamics · Physics 2023-10-26 A. S. Il'yn , A. V. Kopyev , V. A. Sirota , K. P. Zybin

We consider a scale-invariant helical magnetic field generated during inflation. We show that, if the mean magnetic helicity density of such a field is measured, it can be used to determine a lower bound on the duration of inflation. Upper…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-13 Tina Kahniashvili , Axel Brandenburg , Ruth Durrer , Alexander G. Tevzadze , Winston Yin

Using results of numerical simulations and Galactic and galaxy clusters observations, it is shown that the transition from deterministic chaos to hard turbulence in the Galactic and galaxy clusters magnetized plasmas occurs via a…

Astrophysics of Galaxies · Physics 2024-11-28 A. Bershadskii

Observational evidence for dynamo action in spiral galaxies is reviewed, and the capabilities of various theories in explaining the basic features of galactic magnetic fields are discussed. Mean-field dynamo models appear to be unique in…

Astrophysics · Physics 2007-05-23 Anvar Shukurov

The full-sky Planck polarization data at 850um revealed unexpected properties of the E and B mode power spectra of dust emission in the interstellar medium (ISM). The positive cross-correlation between the total dust intensity, T, with the…

Astrophysics of Galaxies · Physics 2019-01-16 Andrea Bracco , Simon Candelaresi , Fabio Del Sordo , Axel Brandenburg

Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles…

Astrophysics · Physics 2009-11-06 Steven Furlanetto , Abraham Loeb

Multi-frequency radio polarimetry of the diffuse Galactic synchrotron background gives new viewpoints on the Galactic magnetic field. Rotation measure maps reveal magnetic structures on arcminute to degree scales, such as a ring in…

Astrophysics · Physics 2015-06-24 M. Haverkorn , P. Katgert , A. G. de Bruyn , F. Heitsch

Despite their ubiquity, the origin of cosmic magnetic fields remains unknown. Various mechanisms have been proposed for their existence including primordial fields generated by inflation, or amplification and injection by compact…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-23 Harley Katz , Sergio Martin-Alvarez , Julien Devriendt , Adrianne Slyz , Taysun Kimm