Large-scale magnetized outflows from the Virgo Cluster spiral NGC 4569

A galactic wind in a ram pressure wind

¹ Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Kraków, Poland e-mail: chris@oa.uj.edu.pl
² Astronomisches Institut, Ruhr-Universität-Bochum, 44780 Bochum, Germany
³ CDS, Observatoire astronomique de Strasbourg, UMR 7550, 11 rue de l'Université, 67000 Strasbourg, France
⁴ Observatoire de Paris, GEPI, CNRS UMR 8111, and Université Paris 7, 5 Place Jules Janssen, 92195 Meudon Cedex, France
⁵ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

Received: 12 July 2005
Accepted: 3 October 2005

Abstract

Using the Effelsberg radio telescope at 4.85 GHz and 8.35 GHz we discovered large symmetric lobes of polarized radio emission around the strongly Hi deficient Virgo cluster spiral galaxy NGC 4569. These lobes extend up to 24 kpc from the galactic disk. Our observations were complemented by 1.4 GHz continuum emission from existing Hi observations. This is the first time that such huge radio continuum lobes are observed in a cluster spiral galaxy. The eastern lobe seems detached and has a flat spectrum typical of in-situ cosmic ray electron acceleration. The western lobe is diffuse and possesses vertical magnetic fields over its whole volume. The lobes are not powered by an AGN, but probably by a nuclear starburst that occurred  Myr ago, producing supernovae. Since the radio lobes are symmetric, they resist ram pressure due to the galaxy's rapid motion within the intracluster medium.