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Astron. Astrophys. 341, 29-43 (1999)

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VLA observations of the giant radio galaxy 3C 449

L. Feretti 1, R. Perley 2, G. Giovannini 1,3 and H. Andernach 4

1 Istituto di Radioastronomia del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy
2 National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 0387, USA
3 Dipartimento di Fisica, Universitá di Bologna, I-40100 Bologna, Italy
4 Departamento de Astronomía, IFUG, Apartado Postal 144, Guanajuato, C.P. 36000, Mexico

Received 4 May 1998 / Accepted 25 September 1998


In this paper we present multifrequency VLA observations of the giant radio galaxy 3C 449. High resolution and sensitivity data were obtained in total intensity and polarized flux at 1.365, 1.445, 1.465, 1.485, 4.685, 4.985 and 8.385 GHz.

The source is characterized by an unresolved core, two opposite symmetric jets, and very extended lobes. These new images show the source morphology in great detail, in particular we detect plumes and wiggles in the low brightness lobes. The source is considerably polarized at all frequencies. We find that the magnetic field orientation is parallel to the jet axis at the very beginning of the jet, and becomes perpendicular at about [FORMULA] (5 kpc) from the core. In the low brightness regions, the magnetic field is circumferential to the edges of the emission region.

The spectral index map between 5 GHz and 8.4 GHz shows that the northern region beyond [FORMULA] from the core has a much flatter spectrum than the southern one.

We analyse the jet dynamics, and conclude that the jets are relativistic at the beginning, and decelerate significantly within [FORMULA](5 kpc) from the core.

We compute the rotation measure, using all seven frequencies between 1.4 and 8.4 GHz. We detect significant rotation measure with values within about [FORMULA]50 rad m-2 of the expected contribution of our Galaxy. The Faraday effect is likely to originate in an external screen, which is most probably the intergalactic medium of the group of galaxies around 3C 449. Moreover, we resolve the effect of the interstellar medium associated with the galaxy 3C 449 itself.

Key words: galaxies: individual: 3C 449 – galaxies: jets – galaxies: magnetic fields – radio continuum: galaxies

Send offprint requests to: lferetti@ira.bo.cnr.it

© European Southern Observatory (ESO) 1999

Online publication: November 26, 1998