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Chyży, K. T.; Urbanik, M.; Soida, M.; Beck, Rainer

doi:10.1023/a:1019587029293

Cited by 55 publications

(85 citation statements)

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“…This magnetic field is just dragged along with the wind, as the energy density of the wind is about 30 times that of the magnetic field. A similar finding was made by Chyzy et al (2000) for the dwarf irregular NGC 4449, which also possesses a low-frequency radio halo (Klein et al 1996). …”

Section: Uli Kleinsupporting

confidence: 80%

Dwarf galaxies and the Magnetisation of the IGM

Klein¹

2008

Proc. IAU

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Abstract. With the operation of LOFAR, a great opportunity exists to shed light on a problem of some cosmological significance. Diffuse radio synchrotron emission not associated to any obvious discrete sources as well as Faraday rotation in clusters of galaxies both indicate that the intergalactic or intracluster medium (IGM, ICM) is pervaded by a weak magnetic field, along with a population of relativistic particles. Both, particles and fields must have been injected into the IGM either by Active Galactic Nuclei (AGN) or by normal star-forming galaxies. Excellent candidates for the latter are starburst dwarf galaxies, which in the framework of hierarchical structure formation must have been around in large numbers. If this is true, one should be able to detect extended synchrotron halos of formerly highly relativistic particles around local starburst or post-starburst dwarf galaxies. With LOFAR, one should easily find these out to the Coma Cluster and beyond.

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Section: Uli Kleinsupporting

confidence: 80%

Dwarf galaxies and the Magnetisation of the IGM

Klein¹

2008

Proc. IAU

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“…In irregular galaxies, both quantities seem to be too low to initiate efficient dynamo action. In contrast, the observations of magnetic field in irregular galaxies indicate that these galaxies could have strong and ordered magnetic fields (e.g., Chyży et al 2000Chyży et al , 2003Kepley et al 2007;Lisenfeld et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Cosmic-ray driven dynamo in the interstellar medium of irregular galaxies

Siejkowski¹,

Soida²,

Otmianowska-Mazur³

et al. 2010

A&A

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Context. Irregular galaxies are usually smaller and less massive than their spiral, S0, and elliptical counterparts. Radio observations indicate that a magnetic field is present in irregular galaxies whose value is similar to that in spiral galaxies. However, the conditions in the interstellar medium of an irregular galaxy are unfavorable for amplification of the magnetic field because of the slow rotation and low shearing rate. Aims. We investigate the cosmic-ray driven dynamo in the interstellar medium of an irregular galaxy. We study its efficiency under the conditions of slow rotation and weak shear. The star formation is also taken into account in our model and is parametrized by the frequency of explosions and modulations of activity. Methods. The numerical model includes a magnetohydrodynamical dynamo driven by cosmic rays that is injected into the interstellar medium by randomly exploding supernovae. In the model, we also include essential elements such as vertical gravity of the disk, differential rotation approximated by the shearing box, and resistivity leading to magnetic reconnection. Results. We find that even slow galactic rotation with a low shearing rate amplifies the magnetic field, and that rapid rotation with a low value of the shear enhances the efficiency of the dynamo. Our simulations have shown that a high amount of magnetic energy leaves the simulation box becoming an efficient source of intergalactic magnetic fields.

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“…Recent radio continuum observations of Virgo Cluster galaxies show also magnetic field structures which are not present in normal galaxies (Soida et al 1996;Vollmer et al, in prep.). NGC 4254, oriented face-on, shows strong radio polarization maxima distributed outside the optical spiral arms in the direction towards the Virgo Cluster center (Soida et al 1996;Chyży et al 2001). The highly inclined galaxy NGC 4522 also shows asymmetric radio polarization asymmetries (Vollmer et al, in prep.…”

Section: Introductionmentioning

confidence: 99%

Magnetic field evolution in galaxies interacting with the intracluster medium

Otmianowska-Mazur

Vollmer

2003

A&A

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Abstract.A fully three-dimensional (3D) magnetohydrodynamical (MHD) model is applied to simulate the evolution of the large-scale magnetic field in cluster galaxies interacting with the intra-cluster medium (ICM). As the model input we use time-dependent gas velocity fields resulting from 3D N-body sticky-particle simulations of a galaxy. The modeled clouds are affected by the ram pressure due to their rapid motion through the ICM in the central part of a cluster. Numerical simulations have shown that after the initial compression phase due to ram pressure, a process of gas re-accretion onto the galactic disk takes place. We find that the gas re-accretion leads to an increase of the total magnetic energy without any dynamo action. The simulated magnetic fields are used to construct the model maps of high-frequency (Faraday rotation-free) polarized radio emission. We show that the evolution of the polarized intensity shows features that are characteristic of different evolutionary stages of an ICM-ISM interaction. The comparison of polarized radio continuum emission maps with our model permits us to determine whether the galaxy is in the compression or in the re-accretion phase. It also provides an important constraint upon the dynamical modeling of ICM-ISM interactions.

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Cited by 55 publications

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Dwarf galaxies and the Magnetisation of the IGM

Dwarf galaxies and the Magnetisation of the IGM

Cosmic-ray driven dynamo in the interstellar medium of irregular galaxies

Magnetic field evolution in galaxies interacting with the intracluster medium

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