EDP Sciences
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Volume 423, Number 1, August III 2004
Page(s) 57 - 64
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20035783

A&A 423, 57-64 (2004)
DOI: 10.1051/0004-6361:20035783

Detection of a radio halo in the Virgo cluster

B. Vollmer1, 2, W. Reich2 and R. Wielebinski2

1  CDS, Observatoire astronomique de Strasbourg, UMR 7550, 11 rue de l'université, 67000 Strasbourg, France
    e-mail: bvollmer@astro.u-strasbg.fr
2  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 2 December 2003 / Accepted 25 March 2004)

New Effelsberg 1.4 GHz observations of the central $10\degr \times 10\degr$ of the Virgo cluster are presented. NVSS data are used to subtract point sources from our map. During the data reduction process special care is taken (i) to disentangle emission from the North Polar Spur from emission from the Virgo cluster, (ii) to disentangle emission from the strong M 87 sidelobes from emission from the Virgo cluster, and (iii) to correct for non-linear ground emission due to the long scans. We detect a low surface brightness radio halo with a flux density of $5\pm1.5$ Jy centered close to the elliptical galaxy M 86. This halo is much weaker than that observed in the Coma cluster. It is reminiscent of a past interaction between the intracluster medium of M 86 and a low density gas, belonging most probably to the Virgo cluster.

Key words: galaxies: clusters: individual: Virgo -- galaxies: intergalactic medium -- radio continuum: general

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