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Simulations are presented of the photoionisation of three dense gas clouds threaded by magnetic fields, showing the dynamical effects of different initial magnetic field orientations and strengths. For moderate magnetic field strengths the…

Astrophysics of Galaxies · Physics 2013-01-08 Jonathan Mackey , Andrew J. Lim

We study the cosmic evolution of the magnetic fields of a large sample of spiral galaxies in a cosmologically representative volume by employing a semi-analytic galaxy formation model and numerical dynamo solver in tandem. We start by…

Astrophysics of Galaxies · Physics 2019-01-03 Luiz Felippe S. Rodrigues , Luke Chamandy , Anvar Shukurov , Carlton M. Baugh , A. Russ Taylor

Primordial magnetic fields (PMFs) play a pivotal role in influencing small-scale fluctuations within the primordial density field, thereby enhancing the matter power spectrum within the context of the $\Lambda$CDM model at small scales.…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-02 Qile Zhang , Shang Li , Xiu-Hui Tan , Jun-Qing Xia

From our radio continuum and polarization observations of a sample of spiral galaxies with different morphological types, inclinations, and star formation rates (SFR) we found that galaxies with low SFR have higher thermal fractions/…

Astrophysics · Physics 2008-06-13 Marita Krause

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

Magnetic fields are observed in star forming regions. However simulations of the late stages of star formation that do not include magnetic fields provide a good fit to the properties of young stars including the initial mass function (IMF)…

Solar and Stellar Astrophysics · Physics 2018-10-17 C. J. Nixon , J. E. Pringle

Magnetic fields constitute an energetic component of the interstellar medium in galaxies and hence can affect the formation of galactic structures. Sensitive resolved radio continuum observations together with statistical studies in galaxy…

Astrophysics of Galaxies · Physics 2018-11-20 Fatemeh S. Tabatabaei

In numerical studies of turbulence, hyperviscosity is often used as a tool to extend the inertial subrange and to reduce the dissipative subrange. By analogy, hyperdiffusivity (or hyperresistivity) is sometimes used in magnetohydrodynamics.…

Astrophysics · Physics 2009-11-07 Axel Brandenburg , Graeme R. Sarson

In the framework of turbulence dynamo, flow motions amplify a weak seed magnetic field through the stretching of field lines. Although the amplification process has been a topic of active research, less attention has been paid to the length…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Jungyeon Cho , Dongsu Ryu

Primordial magnetic fields could explain the large-scale magnetic fields present in the Universe. Inflation and phase transitions in the early Universe could give rise to such fields with unique characteristics. We investigate the…

The role of turbulence in astrophysical environments and its interplay with magnetic fields is still highly debated. In this lecture, we will discuss this issue in the framework of dynamo processes. We will first present a very brief…

Solar and Stellar Astrophysics · Physics 2015-06-12 E. M. de Gouveia Dal Pino , R. Santos-Lima , G. Kowal , D. Falceta-Gonçalves

Turbulence is believed to play important roles in the origin of cosmic magnetism. While it is well known that turbulence can efficiently amplify a uniform or spatially homogeneous seed magnetic field, it is not clear whether or not we can…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Jungyeon Cho

The presence of magnetic fields in many astrophysical objects is due to dynamo action, whereby a part of the kinetic energy is converted into magnetic energy. A turbulent dynamo that produces magnetic field structures on the same scale as…

Astrophysics of Galaxies · Physics 2020-03-19 Amit Seta , Paul J. Bushby , Anvar Shukurov , Toby S. Wood

We perform direct numerical simulations of the equations of magnetohydrodynamics with external random forcing and in the presence of gravity. The domain is divided into two parts: a lower layer where the forcing is helical and an upper…

Solar and Stellar Astrophysics · Physics 2014-10-20 Dhrubaditya Mitra , A. Brandenburg , N. Kleeorin , I. Rogachevskii

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

Dynamo action owing to helically forced turbulence and large-scale shear is studied using direct numerical simulations. The resulting magnetic field displays propagating wave-like behavior. This behavior can be modelled in terms of an…

Astrophysics · Physics 2011-02-11 P. J. Käpylä , A. Brandenburg

Generating a powerful and quasistatic magnetic field within the confines of a tabletop laboratory experiment has proven to be a persistent challenge. The creation of magnetized high-energy-density plasma through such experiments presents…

Magnetic field amplification is needed to accelerate cosmic cays to PeV energies in supernova remants. Escaping cosmic rays trigger a return current in the plasma that drives a non-resonant hybrid instability. We run simulations in which we…

High Energy Astrophysical Phenomena · Physics 2012-09-17 K. M. Schure , A. R. Bell

The generation and evolution of astrophysical magnetic fields occurs largely through the action of turbulence. In many situations, the magnetic field is strong enough to influence many important properties of turbulence itself. Numerical…

Astrophysics · Physics 2007-05-23 Ellen G. Zweibel , Fabian Heitsch , Yuhong Fan

Magnetic fields are often invoked as playing a primary role in star formation and in the formation of high-mass stars. We investigate the effect of magnetic fields on the formation of high-mass cores using the 3-dimensional smoothed…

Astrophysics of Galaxies · Physics 2025-04-04 Katerina Sophia Klos , Ian A. Bonnell , Rowan J. Smith