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We study the influence of initial conditions on the magnetic field amplification during the collapse of a magnetised gas cloud. We focus on the dependence of the growth and saturation level of the dynamo generated field on the turbulent…

Solar and Stellar Astrophysics · Physics 2015-06-04 Sharanya Sur , Christoph Federrath , Dominik R. G. Schleicher , Robi Banerjee , Ralf S. Klessen

Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence preferentially located in the Galactic plane. Correspondingly, we consider the Galactic distribution of…

Astrophysics of Galaxies · Physics 2017-01-25 Siyao Xu , Bing Zhang

We explore the amplification of magnetic fields in the high-redshift Universe. For this purpose, we perform high-resolution cosmological simulations following the formation of primordial halos with \sim10^7 M_solar, revealing the presence…

Supersonic turbulence is believed to be at the heart of star formation. We have performed smoothed particle magnetohydrodynamics (SPMHD) simulations of the small-scale dynamo amplification of magnetic fields in supersonic turbulence. The…

Instrumentation and Methods for Astrophysics · Physics 2016-06-03 Terrence S. Tricco , Daniel J. Price , Christoph Federrath

Is the scaling, \lambda \sim Rm^{1/2}, for the growth rate of small-scale dynamo instability at low magnetic Prandtl numbers and large magnetic Reynolds numbers, Rm, valid in the vicinity of the threshold? Our analysis and even numerical…

Fluid Dynamics · Physics 2010-12-14 Nathan Kleeorin , Igor Rogachevskii

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

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

For a universe with massive neutrinos, cold dark matter, and baryons, we solve the linear perturbation equations analytically in the small-scale limit and find agreement with numerical codes at the 1-2% level. The inclusion of baryons, a…

Astrophysics · Physics 2009-10-30 Wayne Hu , Daniel J. Eisenstein

To power gamma-ray bursts and other high-energy events, large-scale magnetic fields are required to extract rotational energy from compact objects such as black holes and neutron stars. The magnetorotational instability (MRI) is a key…

High Energy Astrophysical Phenomena · Physics 2025-09-17 Alexis Reboul-Salze , Loren E. Held , Kenta Kiuchi

The small-scale turbulent dynamo in the high Prandtl number regime is described in terms of the one-point Fourier space correlators. The second order correlator of this kind is the energy spectrum and it has been previously studied in…

Astrophysics · Physics 2009-11-07 S. Nazarenko , R. J. West , O. Zaboronski

The present work is devoted to the evolution of random solutions of the unforced Burgers and KPZ equations in d-dimensions in the limit of vanishing viscosity. We consider a cellular model and as initial condition assign a value for the…

chao-dyn · Physics 2009-10-31 S. N. Gurbatov

Supersonic turbulence in molecular clouds is a dominant agent that strongly affects the clouds' evolution and star formation activity. Turbulence may be initiated and maintained by a number of processes, acting at a wide range of physical…

Astrophysics of Galaxies · Physics 2014-11-20 C. M. Brunt , M. H. Heyer , M. -M. Mac Low

It is widely accepted that supersonic, magnetised turbulence plays a fundamental role for star formation in molecular clouds. It produces the initial dense gas seeds out of which new stars can form. However, the exact relation between gas…

Astrophysics of Galaxies · Physics 2012-04-13 F. Z. Molina , S. C. O. Glover , C. Federrath , R. S. Klessen

Turbulent motions are essential to the mixing of entrained fluids and are also capable of amplifying weak initial magnetic fields by small-scale dynamo action. Here we perform a systematic study of turbulent mixing in magnetized media,…

Astrophysics of Galaxies · Physics 2015-06-18 Sharanya Sur , Liubin Pan , Evan Scannapieco

Using the magnetohydrodynamic (MHD) description, we develop a nonlinear dynamo model that couples the evolution of the large scale magnetic field with turbulent dynamics of the plasma at small scale by electromotive force (e.m.f.) in the…

Earth and Planetary Astrophysics · Physics 2011-09-29 Giuseppina Nigro , Pierlugi Veltri

Spiral galaxies, including the Milky Way, have large-scale magnetic fields with significant energy densities. The dominant theory attributes these magnetic fields to a large-scale dynamo. We review the current status of dynamo theory and…

Astrophysics of Galaxies · Physics 2023-08-31 Axel Brandenburg , Evangelia Ntormousi

Polyakov has suggested that two dimensional turbulence might be described by a minimal model of conformal field theory. However, there are many minimal models satisfying the same physical inputs as Polyakov's solution (p,q)=(2,21).…

High Energy Physics - Theory · Physics 2010-12-17 G. Ferretti , Z. Yang

We present numerical investigations into three principal properties of the small-scale dynamo in stably stratified turbulence: the onset criterion, the growth rate, and the nature of the magnetic field anisotropy in the kinematic regime.…

Fluid Dynamics · Physics 2021-02-04 Valentin Skoutnev , Jonathan Squire , Amitava Bhattacharjee

We performed numerical simulations of supersonic isothermal turbulence driven by mostly compressive large-scale forcing, using both a static grid and adaptive mesh refinement with an effective resolution N=768^3. After a transient phase…

Many astrophysical bodies harbor magnetic fields that are thought to be sustained by a dynamo process. However, it has been argued that the production of large-scale magnetic fields by mean-field dynamo action is strongly suppressed at…

Astrophysics of Galaxies · Physics 2013-01-22 Fabio Del Sordo , Gustavo Guerrero , Axel Brandenburg