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3D model of magnetic fields evolution in dwarf irregular galaxies

Published online by Cambridge University Press:  08 June 2011

Hubert Siejkowski ,
Marian Soida ,
Katarzyna Otmianowska-Mazur ,
Michał Hanasz  and
Dominik J. Bomans
Hubert Siejkowski
Affiliation:
Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland email: h.siejkowski@oa.uj.edu.pl
Marian Soida
Affiliation:
Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland email: h.siejkowski@oa.uj.edu.pl
Katarzyna Otmianowska-Mazur
Affiliation:
Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland email: h.siejkowski@oa.uj.edu.pl
Michał Hanasz
Affiliation:
Torun Centre for Astronomy, Nicolaus Copernicus University, 87-148 Toruń/Piwnice, Poland
Dominik J. Bomans
Affiliation:
Astronomical Institute of Ruhr-University Bochum, Univeristatsstr. 150/NA7, D-44780 Bochum, Germany
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Abstract

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Radio observations show that magnetic fields are present in dwarf irregular galaxies (dIrr) and its strength is comparable to that found in spiral galaxies. Slow rotation, weak shear and shallow gravitational potential are the main features of a typical dIrr galaxy. These conditions of the interstellar medium in a dIrr galaxy seem to unfavourable for amplification of the magnetic field through the dynamo process. Cosmic-ray driven dynamo is one of the galactic dynamo model, which has been successfully tested in case of the spiral galaxies. We investigate this dynamo model in the ISM of a dIrr galaxy. We study its efficiency under the influence of slow rotation, weak shear and shallow gravitational potential. Additionally, the exploding supernovae are parametrised by the frequency of star formation and its modulation, to reproduce bursts and quiescent phases. We found 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.

Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S274: Advances in Plasma Astrophysics , September 2010 , pp. 389 - 392
Copyright
Copyright © International Astronomical Union 2011

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