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Thermal plasma in the giant lobes of the radio galaxy Centaurus A

Thermal plasma in the giant lobes of the radio galaxy ...

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dc.contributor.author O'Sullivan, S. P. pl
dc.contributor.author Feain, I. J. pl
dc.contributor.author McClure-Griffiths, N. M. pl
dc.contributor.author Ekers, R. D. pl
dc.contributor.author Carretti, E. pl
dc.contributor.author Robishaw, T. pl
dc.contributor.author Mao, S. A. pl
dc.contributor.author Gaensler, B. M. pl
dc.contributor.author Bland-Hawthorn, J. pl
dc.contributor.author Stawarz, Łukasz [SAP11018649] pl
dc.date.accessioned 2015-05-20T18:25:34Z
dc.date.available 2015-05-20T18:25:34Z
dc.date.issued 2013 pl
dc.identifier.issn 0004-637X pl
dc.identifier.uri http://ruj.uj.edu.pl/xmlui/handle/item/7629
dc.language eng pl
dc.title Thermal plasma in the giant lobes of the radio galaxy Centaurus A pl
dc.type JournalArticle pl
dc.abstract.en We present a Faraday rotation measure (RM) study of the diffuse, polarized, radio emission from the giant lobes of the nearest radio galaxy, Centaurus A. After removal of the smooth Galactic foreground RM component, using an ensemble of background source RMs located outside the giant lobes, we are left with a residual RM signal associated with the giant lobes. We find that the most likely origin of this residual RM is from thermal material mixed throughout the relativistic lobe plasma. The alternative possibility of a thin-skin/boundary layer of magnetoionic material swept up by the expansion of the lobes is highly unlikely since it requires, at least, an order of magnitude enhancement of the swept-up gas over the expected intragroup density on these scales. Strong depolarization observed from 2.3 to 0.96 GHz also supports the presence of a significant amount of thermal gas within the lobes; although depolarization solely due to RM fluctuations in a foreground Faraday screen on scales smaller than the beam cannot be ruled out. Considering the internal Faraday rotation scenario, we find a thermal gas number density of \sim 10^{-4} cm^{-3}, implying a total gas mass of \sim 10^{10} \mathit{M}_{\bigodot}within the lobes. The thermal pressure associated with this gas (with temperature kT \sim 0.5 keV, obtained from recent X-ray results) is approximately equal to the non-thermal pressure, indicating that over the volume of the lobes, there is approximate equipartition between the thermal gas, radio-emitting electrons, and magnetic field (and potentially any relativistic protons present). pl
dc.subject.en galaxies: individual (Centaurus A (NGC 5128)) pl
dc.subject.en galaxies: magnetic fields pl
dc.subject.en radio continuum: galaxies pl
dc.description.volume 764 pl
dc.description.number 2 pl
dc.identifier.doi 10.1088/0004-637X/764/2/162 pl
dc.identifier.eissn 1538-4357 pl
dc.title.journal The Astrophysical Journal 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 162 pl
dc.rights.original OTHER; inne; ostateczna wersja wydawcy; po opublikowaniu; 12; pl
.pointsMNiSW [2013 A]: 40

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