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Natural dynamos such as planets and stars generate global scale magnetic field despite the inferred presence of small scale turbulence. Such systems are known as large scale dynamos and are typically driven by convection and influenced by…

Fluid Dynamics · Physics 2022-02-24 Ming Yan , Michael A. Calkins

Young neutron stars (NSs) have magnetic fields $B$ in the range $10^{12}-10^{15}$ G, believed to be generated by dynamo action at birth. We argue that such a dynamo is actually too inefficient to explain the strongest of these fields.…

High Energy Astrophysical Phenomena · Physics 2021-08-24 S. K. Lander

All cool main sequence stars including our Sun are thought to have magnetic fields. Observations of the Sun revealed that even in quiet regions small-scale turbulent magnetic fields are present. Simulations further showed that such magnetic…

Solar and Stellar Astrophysics · Physics 2023-02-01 V. Witzke , H. B. Duehnen , A. I. Shapiro , D. Przybylski , T. S. Bhatia , R. Cameron , S. K. Solanki

We present the results of an extensive Arecibo observational survey of magnetic field strengths in the inter-core regions of molecular clouds to determine their role in the evolution and collapse of molecular clouds as a whole. Sensitive 18…

Astrophysics of Galaxies · Physics 2019-10-16 K. L. Thompson , T. H. Troland , C. Heiles

We consider generation and evolution of small-scale magnetic fields in neutron stars. These fields can be generated by small-scale turbulent dynamo action soon after the collapse when the proto-neutron star is subject to convective and…

Astrophysics · Physics 2009-11-10 V. Urpin , J. Gil

The simplest gauge invariant models of inflationary magnetogenesis are known to suffer from the problems of either large backreaction or strong coupling, which make it difficult to self-consistently achieve cosmic magnetic fields from…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-30 Ricardo J. Z. Ferreira , Rajeev Kumar Jain , Martin S. Sloth

Magnetic fields play a role in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have…

Solar and Stellar Astrophysics · Physics 2016-01-26 D. Stello , M. Cantiello , J. Fuller , D. Huber , R. A. Garcia , T. R. Bedding , L. Bildsten , V. Silva Aguirre

Afterglows of gamma-ray bursts are believed to require magnetic fields much stronger than that of the compressed pre-shock medium. As an alternative to microscopic plasma instabilities, we propose amplification of the field by macroscopic…

Astrophysics · Physics 2009-11-13 Lorenzo Sironi , Jeremy Goodman

Low-mass galaxies radio observations show in many cases surprisingly high levels of magnetic field. The mass and kinematics of such objects do not favour the development of effective large-scale dynamo action. We attempted to check if the…

Astrophysics of Galaxies · Physics 2018-03-14 Hubert Siejkowski , Marian Soida , Krzysztof T. Chyzy

We estimate the magnetic field in the jets of the recently discovered 7 Mpc long Porphyrion system. We use non-detection of the system in gamma-rays to derive a lower bound on the co-moving magnetic field strength at the level of ~10 nG.…

High Energy Astrophysical Phenomena · Physics 2025-04-09 A. Neronov , F. Vazza , A. Brandenburg , C. Caprini

Surface magnetic fields have a strong impact on stellar mass loss and rotation and, as a consequence, on the evolution of massive stars. In this work we study the influence of an evolving dipolar surface fossil magnetic field with an…

Solar and Stellar Astrophysics · Physics 2019-03-27 Z. Keszthelyi , G. Meynet , C. Georgy , G. A. Wade , V. Petit , A. David-Uraz

Large-scale magnetic fields in galaxies are thought to be generated by a turbulent dynamo. However the same turbulence also leads to a small-scale dynamo which generates magnetic noise at a more rapid rate. The efficiency of the large-scale…

Astrophysics · Physics 2020-11-25 K. Subramanian

The present-day Universe is highly magnetized, even though the first magnetic seed fields were most probably extremely weak. To explain the growth of the magnetic field strength over many orders of magnitude fast amplification processes…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jennifer Schober , Dominik Schleicher , Stefano Bovino , Ralf S. Klessen

Are the kG-strength magnetic fields observed in young stars a fossil field left over from their formation or are they generated by a dynamo? We use radiation non-ideal magnetohydrodynamics simulations of the gravitational collapse of a…

Solar and Stellar Astrophysics · Physics 2018-09-12 James Wurster , Matthew R. Bate , Daniel J. Price

We discuss the amplification of magnetic fields by the small-scale dynamo, a process that could efficiently produce strong magnetic fields in the first galaxies. In addition, we derive constraints on the primordial field strength from the…

Cosmology and Nongalactic Astrophysics · Physics 2011-10-14 Dominik R. G. Schleicher , Jennifer Schober , Christoph Federrath , Francesco Miniati , Robi Banerjee , Ralf S. Klessen

We study inhomogeneous magnetised cosmologies through the post-recombination era in the framework of Newtonian gravity and the ideal-magnetohydrodynamic limit. The nonlinear kinematic and dynamic equations are derived and linearised around…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-02 Hera Vasileiou , Christos G. Tsagas

The maximum magnetic field strength generated by Weibel-type plasma instabilities is estimated for typical conditions in the interstellar medium. The relevant kinetic dispersion relations are evaluated by conducting a parameter study both…

High Energy Astrophysical Phenomena · Physics 2015-06-16 R. C. Tautz , J. Triptow

We study generation of magnetic fields by the Biermann mechanism in the pair-instability supernovae explosions of first stars. The Biermann mechanism produces magnetic fields in the shocked region between the bubble and interstellar medium…

A cosmological origin of the magnetic fields in large scale structures of the Universe would require a non-negligible magnetic field in cosmic voids, which, however, remains undetected. Gamma-ray emission from gamma-ray bursts (GRBs) offers…

High Energy Astrophysical Phenomena · Physics 2026-02-24 Lea Burmeister , Paolo Da Vela , Francesco Longo , Guillem Marti-Devesa , Manuel Meyer , Francesco Saturni , Antonio Stamerra , Peter Veres

Very-high energy observations of blazars can be used to constrain the strength of the intergalactic magnetic field. A simplifying assumption which is often made is that of a magnetic field of constant strength composed by randomly oriented…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Chiara Caprini , Stefano Gabici