The z-GAL survey

¹ Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38400 Saint-Martind’Hères, France
² Sorbonne Université, UPMC Université Paris 6 and CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98b 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

^* e-mail: berta@iram.fr

Published online: 28 March 2024

Abstract

The z-GAL survey observed 137 bright Herschel-selected galaxies with the IRAM Northern Extended Millimeter Array (NOEMA) to measure their spectroscopic redshift. It detected several multiple sources and secured the spectroscopic redshift of a total of 165 individual galaxies over the range 0.8 < z < 6.5. The wealth of information provided by the NOEMA spectra allowed us to study the physical properties of these galaxies. By modelling their spectral energy distributions, we determined their dust mass, M_dust, temperature, T_dust, and emissivity index, β_dust and found a significant anti-correlation between T_dust and β_dust. Using the detected ¹²CO lines, we derived the molecular gas mass of the z-GAL sources. Combining the molecular lines and the dust continuum emission, we computed their gas depletion timescales, τ_dep: the z-GAL sample consists mainly of powerful starbursts with τ_dep in the range between 0.1 and 1.0 Gyr, while only ~ 25% belongs to the ‘main sequence’ of star forming galaxies.