Letter to the Editor

High resolution observations of a starburst at z = 0.223: resolved CO(1–0) structure

¹ Observatoire de Paris, LERMA (CNRS: UMR8112), 61 Av. de l'Observatoire, 75014, Paris, France e-mail: francoise.combes@obspm.fr
² Observatorio Astronómico Nacional (OAN), Observatorio de Madrid, Alfonso XII, 3, 28014 Madrid, Spain
³ Observatoire de Bordeaux, Université Bordeaux I, BP 89, 33270 Floirac, France
⁴ Max-Planck-Institut für Astronomie (MPIA), Königstuhl 17, 69117 Heidelberg, Germany
⁵ IEM, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 121, 28006 Madrid, Spain
⁶ Radioastronomie ENS, 24 rue Lhomond, 75005 Paris, France

Received: 13 October 2006
Accepted: 27 October 2006

Abstract

We present the results of mapping the CO(1–0) emission of the ultra-luminous starburst IRAS 11582+3020, with the IRAM interferometer, at ~1´´  resolution. This galaxy was selected from an IRAM-30 m survey of 30 galaxies at moderate redshift () to explore galaxy evolution and, in particular, the efficiency of star formation, in the redshift range filling the gap between local and very high-z objects. The CO emission is kinematically resolved, and about 50% of the total emission found in the 27´´ (97 kpc) single dish beam is not recovered by the interferometer. This indicates that some extended emission may be present on large scales (typically 7–15´´). The FIR-to-CO luminosity ratio follows the trend from local to high-z ultra-luminous starbursts.