Letter to the Editor

Detection of two massive CO systems in 4C 41.17 at z = 3.8

¹ European Southern Observatory, Karl Schwarzschild Straße 2, 85748 Garching, Germany e-mail: cdebreuc@eso.org
² Institut de Radioastronomie Millimétrique, Domaine Universitaire, 38406 St. Martin-d'Hères, France e-mail: neri,downes@iram.fr
³ IGPP/LLNL, L-413, 7000 East Ave, Livermore, CA 94550, USA e-mail: wil@igpp.ucllnl.org
⁴ Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands e-mail: reuland@strw.leidenuniv.nl
⁵ Institut d'Astrophysique de Paris, CNRS & Université Paris 6, 98bis Boulevard Arago, 75014 Paris, France e-mail: omont@iap.fr
⁶ Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁷ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK e-mail: rji@roe.ac.uk

Received: 20 October 2004
Accepted: 26 November 2004

Abstract

We have detected CO(4-3) in the radio galaxy 4C 41.17 with the IRAM Interferometer. The CO is in two massive () systems separated by 18 (13 kpc), and by 400 in velocity, which coincide with two different dark lanes in a deep Lyα image. One CO component coincides with the cm-radio core of the radio galaxy, and its redshift is close to that of the  λ 1640 AGN line. The second CO component is near the base of a cone-shaped region southwest of the nucleus, which resembles the emission-line cones seen in nearby AGN and starburst galaxies. The characteristics of the CO sources and their mm/submm dust continuum are similar to those found in ultraluminous IR galaxies and in some high-z radio galaxies and quasars. The fact that 4C 41.17 contains two CO systems is further evidence for the role of mergers in the evolution of galaxies at high redshift.