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Observations suggest a slower stellar rotation relative to gas rotation in the outer part of the Milky Way Galaxy. This difference could be attributed to an interaction with the interstellar magnetic field. In a simple model, fields of…

Astrophysics of Galaxies · Physics 2016-12-21 Joanna Jałocha , Łukasz Bratek , Jan Pękala , Szymon Sikora , Marek Kutschera

Investigations of the inverse cascade of magnetic helicity are conducted with pseudospectral, three-dimensional direct numerical simulations of forced and decaying incompressible magnetohydrodynamic turbulence. The high-resolution…

Solar and Stellar Astrophysics · Physics 2013-09-23 Wolf-Christian Müller , Shiva Kumar. Malapaka

Spiral galaxies host dynamically important magnetic fields which can affect gas flows in the disks and halos. Total magnetic fields in spiral galaxies are strongest (up to 30 \muG) in the spiral arms where they are mostly turbulent or…

Astrophysics · Physics 2009-06-23 Rainer Beck

Magnetic halos of galaxies are crucial for understanding galaxy evolution, galactic-scale outflows, and feedback from star formation activity. Identifying the magnetised halo of the Milky Way is challenging because of the potential…

A decade ago, there was very limited knowledge of magnetic fields of our Galaxy. The local fields in the Solar vicinity were known to be directed towards a Galactic longitude $l\sim~90^{\circ}$ with reversed directions at smaller…

Astrophysics · Physics 2007-05-23 J. L. Han

A variety of observations impose upper limits at the nano Gauss level on magnetic fields that are coherent on inter-galactic scales while blazar observations indicate a lower bound $\sim 10^{-16}$ Gauss. Such magnetic fields can play an…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-15 Tanmay Vachaspati

Magnetic helicity effects are discussed in laboratory and astrophysical settings. First, dynamo action in Taylor-Green flows is discussed for different boundary conditions. However, because of the lack of scale separation with respect to…

Astrophysics · Physics 2009-06-23 A Brandenburg , P J Käpylä

High velocity gas that does not conform to Galactic rotation is observed throughout the Galaxy's halo. One component of this gas, HI high velocity clouds (HVCs), have attracted attention since their discovery in the 1960s and remain…

Astrophysics of Galaxies · Physics 2017-08-24 Asger Grønnow , Thor Tepper-García , Joss Bland-Hawthorn , Naomi McClure-Griffiths

We present a novel method to search for structures of coherently aligned patterns in ultra-high energy cosmic-ray arrival directions simultaneously across the entire sky. This method can be used to obtain information on the Galactic…

Instrumentation and Methods for Astrophysics · Physics 2022-01-31 Marcus Wirtz , Teresa Bister , Martin Erdmann

Primordial magnetic fields may account for all or part of the fields observed in galaxies. We consider the evolution of the magnetic fields created by pseudoscalar effects in the early universe. Such processes can create force-free fields…

Astrophysics · Physics 2009-10-31 George B. Field , Sean M. Carroll

We present a suite of models of the coherent magnetic field of the Galaxy (GMF) based on new divergence-free parametric functions describing the global structure of the field. The model parameters are fit to the latest full-sky Faraday…

Astrophysics of Galaxies · Physics 2024-08-14 Michael Unger , Glennys R. Farrar

We propose a novel approach to reconstruct the surface magnetic helicity density on the Sun or sun-like stars. The magnetic vector potential is determined via decomposition of vector magnetic field measurements into toroidal and poloidal…

Solar and Stellar Astrophysics · Physics 2019-06-12 Valery V. Pipin , Alexei A. Pevtsov , Yang Liu , Alexander G. Kosovichev

Large scale strong magnetic fields in galaxies are generally thought to have been generated by a mean field dynamo. In order to have generated the fields observed, the dynamo would have had to have operated for a sufficiently long period of…

Astrophysics · Physics 2007-05-23 A. Kandus , R. Opher , S. R. M. Barros

We consider the magnetic helicity balance for the galactic dynamo in the framework of the local dynamo problem, as well as in the no-z model (which includes explicitly the radial distribution of the magnetic fields). When calculating the…

Astrophysics · Physics 2009-11-07 N. Kleeorin , D. Moss , I. Rogachevskii , D. Sokoloff

(Shortened) We observed NGC 253 with the VLA in D-configuration and the Effelsberg 100-m telescope using radio continuum polarimetry. Observations at 6.2 cm and 3.6 cm were combined to calculate the RM distribution and to correct for…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Volker Heesen , Marita Krause , Rainer Beck , Ralf-Jürgen Dettmar

The presence of non-zero helicity in intergalactic magnetic fields (IGMF) has been suggested as a clear signature for their primordial origin. We extend a previous analysis of diffuse Fermi-LAT gamma-ray data from 2.5 to more than 11 years…

High Energy Astrophysical Phenomena · Physics 2020-11-06 M. Kachelriess , B. C. Martinez

For the first time we reconstruct the magnetic helicity density of global axisymmetric field of the Sun using method proposed by Brandenburg et al. (2003) and Pipin et al. (2013). To determine the components of the vector potential, we…

Solar and Stellar Astrophysics · Physics 2015-06-18 V. V. Pipin , A. A. Pevtsov

Previously unobservable mirror asymmetry of the solar magnetic field -- a key ingredient of the dynamo mechanism which is believed to drive the 11-year activity cycle -- has now been measured. This was achieved through systematic monitoring…

Solar and Stellar Astrophysics · Physics 2015-05-14 Hongqi Zhang , T. Sakurai , A. Pevtsov , Yu Gao , Haiqing Xu , D. D. Sokoloff , K. Kuzanyan

The large-scale magnetic fields observed in spiral disc galaxies are often thought to result from dynamo action in the disc plane. However, the increasing importance of Faraday depolarization along any line of sight towards the galactic…

Astrophysics of Galaxies · Physics 2018-03-21 C. J. Nixon , T. O. Hands , A. R. King , J. E. Pringle

The magnetic field within a few hundred parsecs of the center of the Galaxy is an essential component of any description of that region. The field has several pronounced observational manifestations: 1) morphological structures such as…

Astrophysics · Physics 2007-05-23 Mark Morris
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