NOEMA redshift measurements of bright Herschel galaxies^⋆

¹ Institut de Radioastronomie Millimétrique (IRAM), 300 Rue de la Piscine, 38400 Saint-Martin-d’Hères, France
e-mail: neri@iram.fr
² Sorbonne Université, UPMC Université Paris 6 and CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris, France
³ Aix-Marseille Université, CNRS and CNES, Laboratoire d’Astrophysique de Marseille, 38 Rue Frédéric Joliot-Curie, 13388 Marseille, France
⁴ School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, UK
⁵ Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Aichi 464-8602, Japan
⁶ National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
⁷ Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA
⁸ University of California Irvine, Physics & Astronomy, FRH 2174, Irvine, CA 92697, USA
⁹ Instituto Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
¹⁰ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
¹¹ School of Physics and Astronomy, University of Nottingham, University Park, Notthingham NG7 2RD, UK
¹² Department of Astronomy, University of Maryland, College Park, MD 20742, USA
¹³ Instituto Nacional de Astrofísica, Óptica y Electrónica, Astrophysics Department, Apdo 51 y 216, Tonantzintla, Puebla 72000, Mexico
¹⁴ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
¹⁵ Institut for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁶ University of Cape Town, Department of Astronomy, Private Bag X3 Rondebosch, 7701 Cape Town, South Africa
¹⁷ Department of Physics and Astronomy, University of the Western Cape, Private Bag X17, Bellville 7535 Cape Town, South Africa
¹⁸ Istituto Nazionale di Astrofisica, Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
¹⁹ Instituto de Astrofísica e Ciências do Espaço, Tapada da Ajuda, Edifício Leste 1349-018, Lisboa, Portugal
²⁰ Department of Astronomy, Cornell University, Space Sciences Building, Ithaca, NY 14853, USA
²¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
²² Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
²³ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
²⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
²⁵ Leiden University, Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
²⁶ European Southern Observatory, Alonso de Córdova 3107, Casilla, 19001 Vitacura, Santiago, Chile

Received: 25 October 2019
Accepted: 5 December 2019

Abstract

Using the IRAM NOrthern Extended Millimeter Array (NOEMA), we conducted a program to measure redshifts for 13 bright galaxies detected in the Herschel Astrophysical Large Area Survey with S_500 μm ≥ 80 mJy. We report reliable spectroscopic redshifts for 12 individual sources, which are derived from scans of the 3 and 2 mm bands, covering up to 31 GHz in each band, and are based on the detection of at least two emission lines. The spectroscopic redshifts are in the range 2.08 <  z <  4.05 with a median value of z = 2.9 ± 0.6. The sources are unresolved or barely resolved on scales of 10 kpc. In one field, two galaxies with different redshifts were detected. In two cases the sources are found to be binary galaxies with projected distances of ∼140 kpc. The linewidths of the sources are large, with a mean value for the full width at half maximum of 700 ± 300 km s⁻¹ and a median of 800 km s⁻¹. We analyze the nature of the sources with currently available ancillary data to determine if they are lensed or hyper-luminous (L_FIR >  10¹³ L_⊙) galaxies. We also present a reanalysis of the spectral energy distributions including the continuum flux densities measured at 3 and 2 mm to derive the overall properties of the sources. Future prospects based on these efficient measurements of redshifts of high-z galaxies using NOEMA are outlined, including a comprehensive survey of all the brightest Herschel galaxies.