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The emergence of a large scale magnetic field from randomly forced isotropic strongly helical flows is discussed in terms of the inverse cascade of magnetic helicity and the alpha-effect. In simulations of such flows the maximum field…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

Intergalactic magnetic fields are assumed to have been spontaneously generated at the reheating stage of the early Universe, due to vacuum polarization of non-Abelian gauge fields at high temperature. The fact that the screening mass of…

High Energy Physics - Phenomenology · Physics 2015-06-04 E. Elizalde , V. Skalozub

We give a pedagogical introduction to two aspects of magnetic fields in the early universe. We first focus on how to formulate electrodynamics in curved space time, defining appropriate magnetic and electric fields and writing Maxwell…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Kandaswamy Subramanian

We characterize magnetic fields produced during electroweak symmetry breaking by non-dynamical numerical simulations based on the Kibble mechanism. The generated magnetic fields were thought to have an energy spectrum $\propto k^3$ for…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-25 Tanmay Vachaspati , Axel Brandenburg

The origin of galactic and extra-galactic magnetic fields is an unsolved problem in modern cosmology. A possible scenario comes from the idea of these fields emerged from a small field, a seed, which was produced in the early universe…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-14 Hector J. Hortua , Leonardo Castaneda , Juan M. Tejeiro

In early-type stars a fossil magnetic field may be generated during the star formation process or be the result of a stellar merger event. Surface magnetic fields are thought to be erased by (sub)surface convection layers, which typically…

Solar and Stellar Astrophysics · Physics 2020-06-17 Adam S. Jermyn , Matteo Cantiello

Astrophysical processes can contribute to magnetic fields within cosmic voids either through magnetized outflows from the astrophysical large-scale structure or through superposition of dipolar contributions from individual galaxies. Such…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-06 Károly Seller , Günter Sigl

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 study the generation of intergalactic magnetic fields in two models for first-order phase transitions in the early Universe that have been studied previously in connection with the generation of gravitational waves (GWs): the Standard…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-29 John Ellis , Malcolm Fairbairn , Marek Lewicki , Ville Vaskonen , Alastair Wickens

We investigate the influence of cosmic magnetic fields on gravitational wave perturbations, and find exact solutions on large scales. We show that a large-scale magnetic field can generate large-scale non-decaying gravitational waves. In…

Astrophysics · Physics 2009-11-06 Roy Maartens , Christos Tsagas , Carlo Ungarelli

We improve previous calculations of the CMB spectral distortions due to the decay of primordial magnetic fields. We focus our studies on causally generated magnetic fields at the electroweak and QCD phase transitions. We also consider the…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-23 Jacques M. Wagstaff , Robi Banerjee

We analyze the generation of helical magnetic fields during preheating in a model of low-scale electroweak (EW) hybrid inflation. We show how the inhomogeneities in the Higgs field, resulting from tachyonic preheating after inflation, seed…

High Energy Physics - Phenomenology · Physics 2008-12-18 Andres Diaz-Gil , Juan Garcia-Bellido , Margarita Garcia Perez , Antonio Gonzalez-Arroyo

We review our current understanding of galactic dynamo theory, paying particular attention to numerical simulations both of the mean-field equations and the original three-dimensional equations relevant to describing the magnetic field…

Astrophysics of Galaxies · Physics 2014-12-12 Axel Brandenburg

I review some of the mechanisms through which primordial magnetic fields may be created in the electroweak phase transition. I show that no magnetic fields are produced initially from two-bubble collisions in a first-order transition. The…

High Energy Physics - Phenomenology · Physics 2016-10-26 Ola Tornkvist

The origin of large-scale magnetic fields, detected in some low-mass (dwarf and irregular) galaxies via polarised synchrotron emission and Faraday rotation, remained unexplained for a long time. We suggest that mean-field dynamo can be…

Astrophysics of Galaxies · Physics 2019-10-16 Prasanta Bera , Anvar Shukurov , Kandaswamy Subramanian

We argue that ultra-high energy cosmic rays emitted by galaxy clusters result in electric currents in filaments of the large-scale structure that are sufficient to generate magnetic fields in voids of the magnitude of ~1e-12 G and the…

High Energy Astrophysical Phenomena · Physics 2012-02-03 M. S. Pshirkov , P. G. Tinyakov

Primordial magnetic fields are often thought to be the early Universe seeds that have bloomed into what we observe today as galactic and extra-galactic magnetic fields. Owing to their minuscule strength, primordial magnetic fields are very…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-11 Sabir Ramazanov , Federico R. Urban , Alexander Vikman

We propose a primordial-origin model for the composite configurations of global magnetic fields in spiral galaxies. We show that uniform tilted magnetic field wound up into a rotating disk galaxy can evolve into composite magnetic…

Astrophysics of Galaxies · Physics 2015-05-19 Yoshiaki Sofue , Mami Machida , Takahiro Kudoh

We investigate the generation of magnetic field by the Biermann battery in cosmological ionization fronts, using new simulations of the reionization of the universe by stars in protogalaxies. Two mechanisms are primarily responsible for…

Astrophysics · Physics 2009-10-31 Nickolay Y. Gnedin , Andrea Ferrara , Ellen G. Zweibel

Recently the lower bounds of the intergalactic magnetic fields $10^{-16} \sim 10^{-20}$ Gauss are set by gamma-ray observations while it is unlikely to generate such large scale magnetic fields through astrophysical processes. It is known…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-17 Shohei Saga , Maresuke Shiraishi , Kiyotomo Ichiki , Naoshi Sugiyama
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