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Magnetic fields grow quickly, even at early cosmological times, suggesting the action of a small-scale dynamo (SSD) in the interstellar medium (ISM) of galaxies. Many studies have focused on idealized, isotropic, homogeneous, turbulent…

Astrophysics of Galaxies · Physics 2023-02-15 Frederick A. Gent , Mordecai-Mark Mac Low , Maarit J. Korpi-Lagg , Nishant K. Singh

Magnetic fields grow quickly even at early cosmological times, suggesting the action of a small-scale dynamo (SSD) in the interstellar medium of galaxies. Many studies have focused on idealized turbulent driving of the SSD. Here we simulate…

Astrophysics of Galaxies · Physics 2021-04-07 Frederick A. Gent , Mordecai-Mark Mac Low , Maarit J. Kapyla , Nishant K. Singh

Magnetic fields are widely observed in the Universe in virtually all astrophysical objects, from individual stars to entire galaxies, even in the intergalactic medium, but their specific generation has long been debated. Due to the…

Astrophysics of Galaxies · Physics 2017-11-08 Michael Rieder , Romain Teyssier

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

It has been recently shown numerically that a small-scale dynamo (SSD) instability could be possible in solar-like low magnetic Prandtl number plasmas. It has been proposed that the presence of SSD can potentially have a significant impact…

Solar and Stellar Astrophysics · Physics 2025-04-09 Jörn Warnecke , Maarit J. Korpi-Lagg , Matthias Rheinhard , Mariangela Viviani , Ameya Prabhu

Several lines of evidence suggest that protogalactic and galactic environments manage to grow magnetic field very rapidly. This makes the theoretical problem of achieving rapid growth of magnetic fields in such environments difficult.…

Astrophysics · Physics 2009-11-10 D. S. Balsara , J. S. Kim , M. M. Mac Low , G. Mathews

The turbulent small-scale dynamo (SSD) is likely to be responsible for the magnetisation of the interstellar medium (ISM) that we observe in the Universe today. The SSD efficiently converts kinetic energy $E_{\rm kin}$ into magnetic energy…

Astrophysics of Galaxies · Physics 2023-06-28 James R. Beattie , Christoph Federrath , Neco Kriel , Philip Mocz , Amit Seta

The ordered magnetic field observed via polarized synchrotron emission in nearby disc galaxies can be explained by a mean-field dynamo operating in the diffuse interstellar medium (ISM). Additionally, vertical-flux initial conditions are…

Astrophysics of Galaxies · Physics 2016-01-06 A. Bendre , O. Gressel , D. Elstner

In star forming disk galaxies, matter circulation between stars and the interstellar gas, and, in particular the energy input by random and clustered supernova explosions, determine the dynamical and chemical evolution of the ISM, and hence…

Astrophysics · Physics 2009-11-10 Miguel A. de Avillez , Dieter Breitschwerdt

Magnetic field amplification by a fast dynamo is seen in local box simulations of SN-driven ISM turbulence, where the self-consistent emergence of large-scale fields agrees very well with its mean-field description. We accordingly derive…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-25 Detlef Elstner , Oliver Gressel

Observations have suggested substantial departures from pressure equilibrium in the interstellar medium (ISM) in the plane of the Galaxy, even on scales under 50 pc. Nevertheless, multi-phase models of the ISM assume at least locally…

Astrophysics · Physics 2009-11-10 Mordecai-Mark Mac Low , Dinshaw S. Balsara , Jongsoo Kim , Miguel A. Avillez

The role of magnetic fields in the multi-phase interstellar medium (ISM) is explored using magnetohydrodynamic (MHD) simulations that include energy injection by supernova (SN) explosions and allow for dynamo action. Apart from providing…

Astrophysics of Galaxies · Physics 2018-10-03 A. Shukurov , C. C. Evirgen , A. Fletcher , P. J. Bushby , F. A. Gent

I model the multi-phase interstellar medium (ISM) randomly heated and shocked by supernovae, with gravity, differential rotation and other parameters we understand to be typical of the solar neighbourhood. The simulations are 3D extending…

Astrophysics of Galaxies · Physics 2017-12-15 Frederick Gent

The Universe at present is highly magnetized, with fields of the order of a few 10^-5 G and coherence lengths larger than 10 kpc in typical galaxies like the Milky Way. We propose that the magnetic field was amplified to this values already…

Astrophysics of Galaxies · Physics 2015-06-17 Jennifer Schober , Dominik R. G. Schleicher , Ralf S. Klessen

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

The growth and saturation of magnetic field in conducting turbulent media with large magnetic Prandtl numbers are investigated. This regime is very common in low-density hot astrophysical plasmas. During the early (kinematic) stage, weak…

Astrophysics · Physics 2009-11-07 A. A. Schekochihin , S. C. Cowley , G. W. Hammett , J. L. Maron , J. C. McWilliams

We explore the effect of magnetic fields on the vertical distribution and multiphase structure of the supernova-driven interstellar medium (ISM) in simulations that admit dynamo action. As the magnetic field is amplified to become…

Astrophysics of Galaxies · Physics 2019-09-26 C. C. Evirgen , F. A. Gent , A. Shukurov , A. Fletcher , P. J. Bushby

Observations have suggested substantial departures from pressure equilibrium in the interstellar medium (ISM) in the plane of the Galaxy, even on scales under 50 pc. Nevertheless, multi-phase models of the ISM assume at least locally…

Astrophysics · Physics 2007-05-23 Mordecai-Mark Mac Low , Dinshaw Balsara , Miguel A. Avillez , Jongsoo Kim

Small-scale dynamos (SSDs) amplify magnetic fields in turbulent plasmas. Theory predicts nonlinear magnetic energy growth $E_\mathrm{mag} \propto t^{p_\mathrm{nl}}$, but this scaling has not been tested across flow regimes. Using a large…

Magnetohydrodynamical (MHD) dynamos emerge in many different astrophysical situations where turbulence is present, but the interaction between large-scale (LSD) and small-scale dynamos (SSD) is not fully understood. We performed a…

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