Seeking large-scale magnetic fields in a pure-disk dwarf galaxy NGC 2976

2016
journal article
article
cris.lastimport.scopus2024-04-07T17:50:42Z
dc.abstract.enAims. It is still unknown how magnetic field-generation mechanisms could operate in low-mass dwarf galaxies. Here, we present a detailed study of a nearby pure-disk dwarf galaxy NGC 2976. Unlike previously observed dwarf objects, this galaxy possesses a clearly defined disk. We also discuss whether NGC 2976 could serve as a potential source of the intergalactic magnetic field. Methods. For the purpose of our studies, we performed deep multi-frequency polarimetric observations of NGC 2976 with the VLA and Effelsberg radio telescopes. Additionally, we supplement them with re-imaged data from the WSRT-SINGS survey for which a rotation measure (RM) synthesis was performed. A new weighting scheme for the RM synthesis algorithm, consisting of including information about the quality of data in individual frequency channels, was proposed and investigated. Application of this new weighting to the simulated data, as well as to the observed data, results in an improvement of the signal-to-noise ratio in the Faraday depth space. Results. The magnetic field morphology discovered in NGC 2976 consists of a southern polarized ridge. This structure does not seem to be due to just a pure large-scale dynamo process (possibly cosmic-ray driven) at work in this object, as indicated by the RM data and dynamo number calculations. Instead, the field of NGC 2976 is modified by past gravitational interactions and possibly also by ram pressure inside the M 81 galaxy group environment. The estimates of total (7 $\mu G$) and ordered (3 $\mu G$) magnetic field strengths, as well as degree of field order (0.46), which is similar to those observed in spirals, suggest that tidally generated magnetized gas flows can further enhance dynamo action in the object. NGC 2976 is apparently a good candidate for the efficient magnetization of its neighbourhood. It is able to provide an ordered (perhaps also regular) magnetic field into the intergalactic space up to a distance of about 5 kpc. Conclusions. Tidal interactions (and possibly also ram pressure) can lead to the formation of unusual magnetic field morphologies (like polarized ridges) in galaxies out of the star-forming disks, which do not follow any observed component of the interstellar medium (ISM), as observed in NGC 2976. These galaxies are able to provide ordered magnetic fields far out of their main disks.pl
dc.affiliationWydział Fizyki, Astronomii i Informatyki Stosowanej : Instytut – Obserwatorium Astronomicznepl
dc.contributor.authorDrzazga, Robert - 138526 pl
dc.contributor.authorChyży, Krzysztof - 100034 pl
dc.contributor.authorHeald, G. H.pl
dc.contributor.authorElstner, D.pl
dc.contributor.authorGallagher, J. S.pl
dc.date.accessioned2016-06-29T11:12:21Z
dc.date.available2016-06-29T11:12:21Z
dc.date.issued2016pl
dc.date.openaccess12
dc.description.accesstimepo opublikowaniu
dc.description.additionalReproduced with permission from Astronomy & Astrophysics, © ESOpl
dc.description.versionostateczna wersja wydawcy
dc.description.volume589pl
dc.identifier.articleidA12pl
dc.identifier.doi10.1051/0004-6361/201527236pl
dc.identifier.eissn1432-0746pl
dc.identifier.issn0004-6361pl
dc.identifier.projectROD UJ / Ppl
dc.identifier.urihttp://ruj.uj.edu.pl/xmlui/handle/item/28458
dc.languageengpl
dc.language.containerengpl
dc.rightsUdzielam licencji. Uznanie autorstwa - Użycie niekomercyjne - Na tych samych warunkach 4.0 Międzynarodowa*
dc.rights.licenceOTHER
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/4.0/legalcode.pl*
dc.share.typeotwarte czasopismo
dc.subject.engalaxies: dwarfpl
dc.subject.engalaxies: evolutionpl
dc.subject.engalaxies: individual: NGC 2976pl
dc.subject.engalaxies: magnetic fieldspl
dc.subtypeArticlepl
dc.titleSeeking large-scale magnetic fields in a pure-disk dwarf galaxy NGC 2976pl
dc.title.journalAstronomy & Astrophysicspl
dc.typeJournalArticlepl
dspace.entity.typePublication
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