Letter to the Editor

First detection of [CII]158 μm at high redshift: vigorous star formation in the early universe

¹ INAF – Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, 50125 Firenze, Italy e-mail: maiolino@arcetri.astro.it
² IRAM, 300 rue de la Piscine, 38406 St.-Marin-d'Hères, France
³ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁴ Radioastronomisches Institut, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁵ National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
⁶ Department of Physics, San Jose State University, 1 Washington Square, San Jose, CA 95192, USA
⁷ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
⁸ Institut d'Astrophysique de Paris, UMR 7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
⁹ Instituto de Radioastronomia Milimetrica, Avenida Divina Pastora 7, 18012 Granada, Spain
¹⁰ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

Received: 14 June 2005
Accepted: 29 July 2005

Abstract

We report the detection of the fine-structure line of at 157.74  in SDSS J114816.64+525150.3 (hereafter J1148+5251), the most distant known quasar, at , using the IRAM 30-m telescope. This is the first detection of the [Cii] line at high redshift, and also the first detection in a Hyperluminous Infrared Galaxy (). The [Cii] line is detected at a significance level of 8σ and has a luminosity of . The ratio is , about an order of magnitude smaller than observed in local normal galaxies and similar to the ratio observed in local Ultraluminous Infrared Galaxies. The [Cii] line luminosity indicates that the host galaxy of this quasar is undergoing an intense burst of star formation with an estimated rate of ≈. The detection of in SDSS J1148+5251 suggests a significant enrichment of metals at (age of the universe ~870 Myr), although the data are consistent with a reduced carbon to oxygen ratio as expected from chemical evolutionary models of the early phases of galaxy formation.