scholarly journals The origin and evolution of magnetic fields in clusters of galaxies

2008 ◽  
Author(s):  
Luigina Feretti
Keyword(s):  
Magnetic Fields ◽  
Clusters Of Galaxies ◽  
Origin And Evolution

scholarly journals Magnetic Fields in Galaxies

2010 ◽  
Vol 6 (S271) ◽  
pp. 135-144
Author(s):  
Ellen G. Zweibel
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Cosmic Time ◽  
Origin And Evolution ◽  
Cosmological Problem ◽  
Background Turbulence ◽  
Multicomponent Gas ◽  
Magnetic Buoyancy ◽  
Galactic Dynamos

AbstractThe origin and evolution of magnetic fields in the Universe is a cosmological problem. Although exotic mechanisms for magneotgenesis cannot be ruled out, galactic magnetic fields could have been seeded by magnetic fields from stars and accretion disks, and must be continuously regenerated due to the ongoing replacement of the interstellar medium. Unlike stellar dynamos, galactic dynamos operate in a multicomponent gas at low collisionality and high magnetic Prandtl number. Their background turbulence is highly compressible, the plasma β ~ 1, and there has been time for only a few large exponentiation times at large scale over cosmic time. Points of similarity include the importance of magnetic buoyancy, the large range of turbulent scales and tiny microscopic scales, and the coupling between the magnetic field and certain properties of the flow. Understanding the origin and maintenance of the large scale galactic magnetic field is the most challenging aspect of the problem.

scholarly journals Dynamo in Astrophysics

1990 ◽  
Vol 140 ◽  
pp. 83-89
Author(s):  
A.A. Ruzmaikin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Turbulent Flow ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Clusters Of Galaxies ◽  
Magnetic Structures ◽  
Random Magnetic Field ◽  
Astrophysical Objects

The fast dynamo acting in a turbulent flow explains the origin of magnetic fields in astrophysical objects. Stellar cycles and large-scale magnetic fields in spiral galaxies reflect the behaviour of a mean magnetic field. Intermittent magnetic structures in clusters of galaxies are associated with random magnetic field.

scholarly journals Cosmic‐Ray Protons and Magnetic Fields in Clusters of Galaxies and Their Cosmological Consequences

1997 ◽  
Vol 477 (2) ◽  
pp. 560-567 ◽  
Author(s):  
Torsten A. Ensslin ◽  
Peter L. Biermann ◽  
Philipp P. Kronberg ◽  
Xiang‐Ping Wu
Keyword(s):  
Magnetic Fields ◽  
Cosmic Ray ◽  
Clusters Of Galaxies

scholarly journals Origin of strong magnetic fields in Milky Way-like galaxies

2015 ◽  
Vol 11 (S317) ◽  
pp. 274-275
Author(s):  
Alexander M. Beck
Keyword(s):  
Magnetic Fields ◽  
Galaxy Formation ◽  
Milky Way ◽  
Cosmic Time ◽  
Strong Magnetic Fields ◽  
Origin And Evolution ◽  
The Universe

AbstractMagnetic fields are observed on all scales in the Universe (see e.g. Kronberg 1994), but little is known about the origin and evolution of those fields with cosmic time. Seed fields of arbitrary source must be amplified to present-day values and distributed among cosmic structures. Therefore, the emergence of cosmic magnetic fields and corresponding dynamo processes (see e.g. Zel'dovich et al. 1983; Kulsrud et al. 1997) can only be jointly understood with the very basic processes of structure and galaxy formation (see e.g. Mo et al. 2010).

scholarly journals Magnetic fields in clusters of galaxies

2004 ◽  
Vol 48 (11-12) ◽  
pp. 1145-1150 ◽  
Author(s):  
L. Feretti ◽  
M. Johnston-Hollitt
Keyword(s):  
Magnetic Fields ◽  
Clusters Of Galaxies

scholarly journals Cosmic rays in magnetized intracluster plasma

2009 ◽  
Vol 5 (H15) ◽  
pp. 459-460
Author(s):  
L. Feretti ◽  
A. Bonafede ◽  
G. Giovannini ◽  
F. Govoni ◽  
M. Murgia
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Observational Data ◽  
Clusters Of Galaxies ◽  
Merger Activity ◽  
Rotation Measure ◽  
Field Coherence

A breakthrough in the studies of magnetic fields in clusters of galaxies has been reached in recent years from the analysis of the Rotation Measure of sources seen through the magnetized cluster medium (Govoni & Feretti 2004). The results obtained can be summarized as follows: (i) magnetic fields are present in all clusters; (ii) at the center of clusters undergoing merger activity the field strenght is around 1 μG, whereas at the center of relaxed cooling core clusters the intensity is much higher (~ 10 μG); (iii) a model involving a single magnetic field coherence scale is not suitable to describe the observational data, because of different scales of field ordering and tangling.

scholarly journals Measurements of Cosmic Magnetism with LOFAR and SKA

2007 ◽  
Vol 5 ◽  
pp. 399-405 ◽  
Author(s):  
R. Beck
Keyword(s):  
Magnetic Fields ◽  
Interstellar Medium ◽  
Milky Way ◽  
Intergalactic Medium ◽  
Low Frequency ◽  
Radio Telescopes ◽  
New Era ◽  
Origin And Evolution ◽  
Central Regions ◽  
Nearby Galaxies

Abstract. The origin of magnetic fields in stars, galaxies and clusters is an open problem in astrophysics. The next-generation radio telescopes Low Frequency Array (LOFAR) and Square Kilometre Array (SKA) will revolutionize the study of cosmic magnetism. "The origin and evolution of cosmic magnetism" is a key science project for SKA. The planned all-sky survey of Faraday rotation measures (RM) at 1.4 GHz will be used to model the structure and strength of the magnetic fields in the intergalactic medium, the interstellar medium of intervening galaxies, and in the Milky Way. A complementary survey of selected regions at around 200 MHz is planned as a key project for LOFAR. Spectro-polarimetry applied to the large number of spectral channels available for LOFAR and SKA will allow to separate RM components from distinct foreground and background regions and to perform 3-D Faraday tomography of the interstellar medium of the Milky Way and nearby galaxies. – Deep polarization mapping with LOFAR and SKA will open a new era also in the observation of synchrotron emission from magnetic fields. LOFAR's sensitivity will allow to map the structure of weak, extended magnetic fields in the halos of galaxies, in galaxy clusters, and possibly in the intergalactic medium. Polarization observations with SKA at higher frequencies (1–10 GHz) will show the detailed magnetic field structure within the disks and central regions of galaxies, with much higher angular resolution than present-day radio telescopes.

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