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A NOEMA Spectroscopic Redshift Survey of Bright Herschel Galaxies

z-GAL is an IRAM Large Program conducted with the Northern Extended Millimeter Array. It is a world-wide collaboration aimed at measuring spectroscopic redshifts for a large (137 sources) sample of the brightest (S500um > 80 mJy) galaxies selected from the Herschel H-ATLAS, HerMES and HerS surveys.

The principal investigators of the project are P. Cox (IAP/CNRS, France), T. Bakx (Nagoya, Japan / Chalmers, Sweden) and H. Dannerbauer (IAC, Spain). The z-GAL consortium includes 38 members that are active in 15 countries including France, Germany, Spain, UK, Sweden, Italy, The Netherlands, Denmark, Poland, USA, Japan, Mexico, Chile, South-Africa and Australia.

Reliable spectroscopic redshift measurements were derived for 99% of the sources, based on the detection of at least two emission lines. This makes it the largest survey of high-z galaxies with unambiguous redshifts to date. The spectroscopic redshifts are in the range 0.8 < z < 6.5, with a median of z = 2.56, centered on the peak epoch of galaxy evolution.

A series of three papers presents the initial findings from the z-GAL survey, namely: (i) Paper I describes the selected sample, the observations and the details of the data processing, and summarizes the basic results of the survey (Cox et al. 2023, A&A, in the process of revision); (ii) Paper II discusses the continuum emission of the sources and presents a detailed study of their dust properties and evolution with redshift (Ismail et al. 2023, A&A, in the process of revision); (iii) Paper III reports on the physical properties of the sources derived from the molecular and atomic gas and the dust, including the excitation conditions, the depletion time scales and first estimates of the stellar masses (Berta et al. 2023, A&A, in the process of revision).

The link below provides access to the baseline data products of the z-GAL survey. The archive currently contains only the uv-tables for spectral lines and continuum, in GILDAS and FITS format, but will be filled out with more data over time. The README file provides a detailed description of the data release together with other relevant information. The official z-GAL repository is located at IRAM.

Please do not hesitate to contact Pierre Cox and collaborators to inform them about your use of the data for further scientific studies. Other peer-reviewed publications based on the results of pilot programs to the z-GAL survey are: Stanley et al. (2023) ApJ 945, 24; Berta et al. (2021) A&A 646, A122; Neri et al. (2020) A&A 635, A7.

The following acknowledgement is appreciated: “This work made use of z-GAL – A NOEMA spectroscopic survey of bright Herschel galaxies”. An acknowledgment of z-GAL is welcome if data are used in public presentations.