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In this exploratory submission we present the visualization of the largest interstellar turbulence simulations ever performed, unravelling key astrophysical processes concerning the formation of stars and the relative role of magnetic…

Cosmic rays (CRs) are transported out of the galaxy by diffusion and advection due to streaming along magnetic field lines and resonant scattering off self-excited Magneto-Hydro-Dynamic (MHD) waves. Thus momentum is transferred to the…

Astrophysics of Galaxies · Physics 2019-10-02 E. A. Dorfi , D. Steiner , F. Ragossnig , D. Breitschwerdt

The 3-D magnetohydrodynamic (MHD) Anelastic Spherical Harmonic (ASH) code, using slope-limited diffusion, is employed to capture convective and dynamo processes achieved in a global-scale stellar convection simulation for a model solar-mass…

Solar and Stellar Astrophysics · Physics 2015-08-26 Kyle Augustson , Allan Sacha Brun , Mark Miesch , Juri Toomre

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

Spectropolarimetric observations show that many low-mass stars possess large-scale poloidal magnetic fields with considerable dipole component, which in some cases exhibit temporal dynamics - cycles or reversals. Although it is widely…

Solar and Stellar Astrophysics · Physics 2025-07-02 Anna Guseva , Ludovic Petitdemange , Charly Pinçon

Recent years have seen many arguments for cosmic rays (CRs) as an important influence on galactic and circumgalactic (CGM) physics, star and galaxy formation. We present a pedagogical overview of state-of-the-art modeling of…

Astrophysics of Galaxies · Physics 2026-05-11 Philip F. Hopkins

We present initial results from the first 3-dimensional numerical magnetohydrodynamical (MHD) simulations of magnetic field evolution in merging clusters of galaxies. Within the framework of idealized initial conditions similar to our…

Astrophysics · Physics 2009-10-31 K. Roettiger , J. M. Stone , J. O. Burns

The current dynamo paradigm for the Sun and sun-like stars places the generation site for strong toroidal magnetic structures deep in the solar interior. Sunspots and star-spots on sun-like stars are believed to arise when sections of these…

Solar and Stellar Astrophysics · Physics 2015-05-30 Nicholas J. Nelson , Benjamin P. Brown , Allan Sacha Brun , Mark S. Miesch , Juri Toomre

We present non-radiative, cosmological zoom-simulations of galaxy cluster formation with magnetic fields and (anisotropic) thermal conduction of one very massive galaxy cluster with a mass at redshift zero that corresponds to…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-20 Ulrich P. Steinwandel , Ludwig M. Boess , Klaus Dolag , Harald Lesch

In this paper we present the first set of 3D magnetohydrodynamic (MHD) simulations performed with the riemann geomesh code. We study the dynamics of the magnetically channeled winds of magnetic massive stars in full three dimensions using a…

Solar and Stellar Astrophysics · Physics 2023-06-13 Sethupathy Subramanian , Dinshaw S. Balsara , Asif ud-Doula , Marc Gagné

Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. $10^{15}$ eV. A stronger…

High Energy Astrophysical Phenomena · Physics 2016-03-16 Maria Victoria del Valle , Alexandre Lazarian , Reinaldo Santos-Lima

We present a model for the seeding and evolution of magnetic fields in protogalaxies. Supernova (SN) explosions during the assembly of a protogalaxy provide magnetic seed fields, which are subsequently amplified by compression, shear flows…

Astrophysics of Galaxies · Physics 2015-06-16 Alexander M. Beck , Klaus Dolag , Harald Lesch , Philipp P. Kronberg

A detailed understanding of cosmic-ray transport in galactic halos is essential for explaining various observations, such as the radio continuum measurements of synchrotron radiation from energetic electrons. Of central importance is the…

Astrophysics of Galaxies · Physics 2025-07-14 J. Kleimann , H. Fichtner , M. Stein , R. -J. Dettmar , D. J. Bomans , S. Oughton

We use high-resolution MHD simulations of isolated disk galaxies to investigate the co-evolution of magnetic fields with a self-regulated, star-forming interstellar medium (ISM). The simulations are conducted using the Ramses AMR code on…

Astrophysics of Galaxies · Physics 2024-06-05 Hector Robinson , James Wadsley

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

Magnetohydrodynamic (MHD) simulations have been used to study disk accretion to a rotating magnetized star with an aligned dipole moment. Quiescent initial conditions were developed in order to avoid the fast initial evolution seen in…

Astrophysics · Physics 2009-11-07 M. M. Romanova , G. V. Ustyugova , A. V. Koldoba , R. V. E. Lovelace

In the present paper we construct maps of polarized synchrotron radio emission of a whole galaxy, based on local models of the cosmic ray (CR) driven dynamo. We perform numerical simulations of the dynamo in local Cartesian domains, with…

We describe the Stagger Code for simulations of magneto-hydrodynamic (MHD) systems. This is a modular code with a variety of physics modules that will let the user run simulations of deep stellar atmospheres, sunspot formation, stellar…

Instrumentation and Methods for Astrophysics · Physics 2024-05-07 Robert F. Stein , Åke Nordlund , Remo Collet , Regner Trampedach

We use global MHD galaxy simulations to investigate the effects of spiral arms on the evolution of magnetic fields and star formation within a self-regulated interstellar medium (ISM). The same galaxy is simulated twice: once with…

Astrophysics of Galaxies · Physics 2025-06-23 Hector Robinson , James Wadsley , J. A. Sellwood , Ralph E. Pudritz

We present results of three-dimensional, fully nonlinear MHD simulations of a large-scale magnetic field evolution in a barred galaxy. The model does not take into consideration the dynamo process. We find that the obtained magnetic field…

Astrophysics of Galaxies · Physics 2009-11-13 B. Kulesza-Żydzik , K. Kulpa-Dybeł , K. Otmianowska-Mazur , G. Kowal , M. Soida