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3D numerical simulations of magnetic field evolution in barred galaxies and in spiral galaxies under influence of tidal forces

Published online by Cambridge University Press:  08 June 2011

Katarzyna Otmianowska-Mazur ,
Katarzyna Kulpa-Dybeł ,
Barbara Kulesza-Żydzik ,
Hubert Siejkowski  and
Grzegorz Kowal
Katarzyna Otmianowska-Mazur
Affiliation:
Astronomical Observatory, Jagiellonian University, ul Orla 171, 30-244, Kraków, Poland email: [email protected]
Katarzyna Kulpa-Dybeł
Affiliation:
Astronomical Observatory, Jagiellonian University, ul Orla 171, 30-244, Kraków, Poland email: [email protected]
Barbara Kulesza-Żydzik
Affiliation:
Astronomical Observatory, Jagiellonian University, ul Orla 171, 30-244, Kraków, Poland email: [email protected]
Hubert Siejkowski
Affiliation:
Astronomical Observatory, Jagiellonian University, ul Orla 171, 30-244, Kraków, Poland email: [email protected]
Grzegorz Kowal
Affiliation:
Astronomical Observatory, Jagiellonian University, ul Orla 171, 30-244, Kraków, Poland email: [email protected] Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, EP 05508-900, Sao Paulo, Brazil email: [email protected]
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Abstract

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We present the results of the three-dimensional, fully non-linear MHD simulations of the large-scale magnetic field evolution in a barred galaxy with the back reaction of magnetic field to gas. We also include the process of the cosmic-ray driven dynamo. In addition, we check what physical processes are responsible for the magnetic field evolution in the tidally influenced spiral galaxies. We solve the MHD equations for the gas and magnetic field in a spiral galaxy with gravitationally prescribed bulge, disk and halo which travels along common orbit with the second body. In order to compare our modeling results with the observations we also construct the maps of high-frequency (Faraday rotation-free) polarized radio emission from the simulated magnetic fields. The model accounts for the effects of projection and limited resolution.

We found that the obtained magnetic field configurations are highly similar to the observed maps of the polarized intensity of barred galaxies, because the modeled vectors form coherent structures along the bar and spiral arms. We also found a physical explanation of the problem of inconsistency between the velocity and magnetic fields character present in this type of galaxies. Due to the dynamical influence of the bar, the gas forms spiral waves which go radially outward. Each spiral arm forms the magnetic arm which stays much longer in the disk than the gaseous spiral structure. The modeled total energy of magnetic field and magnetic flux grows exponentially due to the action of the cosmic-ray driven dynamo. We also obtained the polarization maps of tidally influenced spiral galaxies which are similar to observations.

Keywords

galaxies: evolutionmagnetic fieldsISM: cosmic raysmethods: numericalMHD
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S274: Advances in Plasma Astrophysics , September 2010 , pp. 381 - 384
Copyright
Copyright © International Astronomical Union 2011

References

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