The influence of the cluster environment on the large-scale radio continuum emission of 8 Virgo cluster spirals

¹ CDS, Observatoire astronomique de Strasbourg, UMR 7550, 11 rue de l'université, 67000 Strasbourg, France e-mail: bvollmer@astro.u-strasbg.fr
² Astronomical Observatory, Jagiellonian University, Kraków, Poland
³ Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA
⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁵ Department of Astronomy, Columbia University, 538 West 120th Street, New York, NY 10027, USA

Received: 3 November 2009
Accepted: 11 January 2010

Abstract

The influence of the environment on the polarized and total power radio continuum emission of cluster spiral galaxies is investigated. We present deep scaled array VLA 20 and 6 cm observations including polarization of 8 Virgo spiral galaxies. These data are combined with existing optical, Hi, and Hα data. Ram pressure compression leads to sharp edges of the total power distribution at one side of the galactic disk. These edges coincide with Hi edges. In edge-on galaxies the extraplanar radio emission can extend further than the Hi emission. In the same galaxies asymmetric gradients in the degree of polarization give additional information on the ram pressure wind direction. The local total power emission is not sensitive to the effects of ram pressure. The radio continuum spectrum might flatten in the compressed region only for very strong ram pressure. This implies that neither the local star formation rate nor the turbulent small-scale magnetic field are significantly affected by ram pressure. Ram pressure compression occurs mainly on large scales (1 kpc) and is primarily detectable in polarized radio continuum emission.