z-GAL: A NOEMA spectroscopic redshift survey of bright Herschel galaxies

II. Dust properties^⋆

¹ Aix-Marseille Université, CNRS and CNES, Laboratoire d’Astrophysique de Marseille, 38 rue Frédéric Joliot-Curie, 13013 Marseille, France
e-mail: diana.ismail@lam.fr
² Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38400 Saint-Martin-d’Hères, France
³ Sorbonne Université, UPMC Université Paris 6 and CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
⁴ Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA
⁵ Cosmic DAWN Centre Radmandsgade 62, 2200 Copenhagen N, Denmark
⁶ Departement of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
⁷ Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Aichi 464-8602, Japan
⁸ National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan
⁹ Instituto Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
¹⁰ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
¹¹ University of California Irvine, Department of Physics & Astronomy, FRH 2174, Irvine, CA 92697, USA
¹² National Centre for Nuclear Research, ul. Pasteura 7, 02-093 Warsaw, Poland
¹³ INAF – Osservatorio astronomico d’Abruzzo, Via Maggini, SNC 64100 Teramo, Italy
¹⁴ Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
¹⁵ Leiden University, Leiden Observatory, PO Box 9513 2300 RA Leiden, The Netherlands
¹⁶ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
¹⁷ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹⁸ Department of Physics and Astronomy, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, South Africa
¹⁹ UK ALMA Regional Center Node, Jodrell Bank Center for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
²⁰ Dipartimento di Fisica & Astronomia “G. Galilei”, Università di Padova, vicolo dell’Osservatorio 3, Padova 35122, Italy
²¹ School of Physics and Astronomy, University of Nottingham, University Park, Notthingham NG7 2RD, UK
²² School of Physics and Astronomy, Cardiff University, Queens Building, The Parade, Cardiff CF24 3AA, UK
²³ Instituto Nacional de Astrofísica, Óptica y Electrónica, Astrophysics Department, Apdo 51 y 216, Tonantzintla, Puebla 72000, Mexico
²⁴ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
²⁵ Department of Physics and Astronomy, Macquarie University, North Ryde, New South Wales, Australia
²⁶ School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin D02 XF86, Ireland
²⁷ Institut for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
²⁸ I. Physikalisches Institut, Iniversität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany
²⁹ Centre de Recherche Astrophysique de Lyon – CRAL, CNRS UMR 5574, UCBL1, ENS Lyon, 9 avenue Charles André, 69230 Saint-Genis-Laval, France
³⁰ Department of Physics and Astronomy, University of the Western Cape, Private Bag X17, Bellville, 7535 Cape Town, South Africa
³¹ Istituto Nazionale di Astrofisica, Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
³² Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, 763-0355 Santiago de Chile, Chile
³³ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla, 19001 Santiago de Chile, Chile

Received: 3 May 2023
Accepted: 5 July 2023

Abstract

We present the dust properties of 125 bright Herschel galaxies selected from the z-GAL NOEMA spectroscopic redshift survey. All the galaxies have precise spectroscopic redshifts in the range 1.3 < z < 5.4. The large instantaneous bandwidth of NOEMA provides an exquisite sampling of the underlying dust continuum emission at 2 and 3 mm in the observed frame, with flux densities in at least four sidebands for each source. Together with the available Herschel 250, 350, and 500 μm and SCUBA-2 850 μm flux densities, the spectral energy distribution (SED) of each source can be analyzed from the far-infrared to the millimeter, with a fine sampling of the Rayleigh-Jeans tail. This wealth of data provides a solid basis to derive robust dust properties, in particular the dust emissivity index (β) and the dust temperature (T_dust). In order to demonstrate our ability to constrain the dust properties, we used a flux-generated mock catalog and analyzed the results under the assumption of an optically thin and optically thick modified black body emission. The robustness of the SED sampling for the z-GAL sources is highlighted by the mock analysis that showed high accuracy in estimating the continuum dust properties. These findings provided the basis for our detailed analysis of the z-GAL continuum data. We report a range of dust emissivities with β ∼ 1.5 − 3 estimated up to high precision with relative uncertainties that vary in the range 7%−15%, and an average of 2.2 ± 0.3. We find dust temperatures varying from 20 to 50 K with an average of T_dust ∼ 30 K for the optically thin case and T_dust ∼ 38 K in the optically thick case. For all the sources, we estimate the dust masses and apparent infrared luminosities (based on the optically thin approach). An inverse correlation is found between T_dust and β with β ∝ T_dust^−0.69, which is similar to what is seen in the local Universe. Finally, we report an increasing trend in the dust temperature as a function of redshift at a rate of 6.5 ± 0.5 K/z for this 500 μm-selected sample. Based on this study, future prospects are outlined to further explore the evolution of dust temperature across cosmic time.