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3D global simulations of a cosmic-ray-driven dynamo in dwarf galaxies

3D global simulations of a cosmic-ray-driven dynamo ...

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dc.contributor.author Siejkowski, Hubert pl
dc.contributor.author Otmianowska-Mazur, Katarzyna [SAP11010837] pl
dc.contributor.author Soida, Marian [SAP11014010] pl
dc.contributor.author Bomans, Dominik J. pl
dc.contributor.author Hanasz, Michał pl
dc.date.accessioned 2015-02-23T18:15:59Z
dc.date.available 2015-02-23T18:15:59Z
dc.date.issued 2014 pl
dc.identifier.issn 0004-6361 pl
dc.identifier.uri http://ruj.uj.edu.pl/xmlui/handle/item/3276
dc.language eng pl
dc.title 3D global simulations of a cosmic-ray-driven dynamo in dwarf galaxies pl
dc.type JournalArticle pl
dc.abstract.en Star-forming dwarf galaxies can be seen as the local proxies of the high-redshift building blocks of more massive galaxies according to the current paradigm of the hierarchical galaxy formation. They are low-mass objects, and therefore their rotation speed is very low. Several galaxies are observed to show quite strong magnetic fields. These cases of strong ordered magnetic fields seem to correlate with a high, but not extremely high, star formation rate. Aims. We investigate whether these magnetic fields could be generated by the cosmic-ray-driven dynamo. The environment of a dwarf galaxy is unfavourable for the large-scale dynamo action because of the very slow rotation that is required to create the regular component of the magnetic field. Methods. We built a 3D global model of a dwarf galaxy that consists of two gravitational components: the stars and the dark-matter halo described by the purely phenomenological profile proposed previously. We solved a system of magnetohydrodynamic equations that include an additional cosmic-ray component described by the fluid approximation. Results. We found that the cosmic-ray-driven dynamo can amplify the magnetic field with an exponential growth rate. The e-folding time is correlated with the initial rotation speed. The final mean value of the azimuthal flux for our models is on the order of few μG and the system reaches its equipartition level. The results indicate that the cosmic-ray-driven dynamo is a process that can explain the magnetic fields in dwarf galaxies. pl
dc.subject.en magnetohydrodynamics (MHD) pl
dc.subject.en dynamo pl
dc.subject.en galaxies: magnetic fields pl
dc.subject.en galaxies: dwarf pl
dc.subject.en methods: numerical pl
dc.description.volume 562 pl
dc.identifier.doi 10.1051/0004-6361/201220367 pl
dc.identifier.eissn 1432-0746 pl
dc.title.journal Astronomy and Astrophysics pl
dc.language.container eng pl
dc.affiliation Wydział Fizyki, Astronomii i Informatyki Stosowanej : Instytut – Obserwatorium Astronomiczne pl
dc.subtype Article pl
dc.identifier.articleid A136 pl
dc.rights.original OTHER; otwarte czasopismo; ostateczna wersja wydawcy; po opublikowaniu; 12 pl
.pointsMNiSW [2014 A]: 35

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