The GOGREEN and GCLASS surveys: first data release

Abstract

We present the first public data release of the GOGREEN and GCLASS surveys of galaxies in dense environments, spanning a redshift range 0.8 < z < 1.5. The surveys consist of deep, multiwavelength photometry and extensive Gemini GMOS spectroscopy of galaxies in 26 overdense systems ranging in halo mass from small groups to the most massive clusters. The objective of both projects was primarily to understand how the evolution of galaxies is affected by their environment, and to determine the physical processes that lead to the quenching of star formation. There was an emphasis on obtaining unbiased spectroscopy over a wide stellar mass range (M ≳ 2 × 1010 M⊙), throughout and beyond the cluster virialized regions. The final spectroscopic sample includes 2771 unique objects, of which 2257 have reliable spectroscopic redshifts. Of these, 1704 have redshifts in the range 0.8 < z < 1.5, and nearly 800 are confirmed cluster members. Imaging spans the full optical and near-infrared wavelength range, at depths comparable to the UltraVISTA survey, and includes HST/WFC3 F160W (GOGREEN) and F140W (GCLASS). This data release includes fully reduced images and spectra, with catalogues of advanced data products including redshifts, line strengths, star formation rates, stellar masses and rest-frame colours. Here we present an overview of the data, including an analysis of the spectroscopic completeness and redshift quality.

The GOGREEN survey: dependence of galaxy properties on halo mass at z > 1 and implications for environmental quenching

“…A1 we show the correlation between z/(1 + z spec ) and 1 + z spec , for all galaxies in COSMOS and SXDF with available spectroscopic redshifts, where z = z phot − z spec . These include deep spectroscopy focused on the 1 < z < 1.5 regime by GOGREEN (Balogh et al 2021). For UltraVISTA DR3 (not shown), there is no significant bias, up to z ∼ 2.…”

“…Since the average rest-frame UVJ colours and photometric redshifts do not noticeably differ between UltraVISTA DR1 and DR3, we do not make the adjustments to colours or photometric redshifts that Table 1. Group names correspond to those in Gozaliasl et al (2019) and Finoguenov et al (2010) for COSMOS and SXDF, respectively; names in boldface are those included in the GOGREEN (Balogh et al 2021) spectroscopic survey. SXDF76XGG has been split into 'a' and 'b' to identify the foreground group; the original X-ray mass estimate for M 200c, X has been retained only for the higher redshift system.…”

“…Column 5 is the group quality flag. A flag value of 0 denotes a group with confirmed redshift from GOGREEN (Balogh et al 2021). Other flag numbers are based on the Gozaliasl et al (2019) catalogue: 1 for secure X-ray emission with well-defined centre and at least one spectroscopic member, and 2 for a system that has some X-ray contamination from foreground or background systems.…”

“…We compute the quiescent fraction (f Q ) and QFE for these systems, as a function of stellar mass. The result is then compared with higher mass clusters at 1 < z < 1.5 from the GOGREEN survey (Balogh et al 2021), and a compilation of lower redshift samples at 0 < z < 0.2 and 0.5 < z < 0.7 that span a similar range of halo mass as our 1 < z < 1.5 samples.…”

“…This can be achieved with samples of groups and clusters with reliable halo mass estimates. The GOGREEN survey (Balogh et al 2017(Balogh et al , 2021 was designed with this goal, and provides a sample of 21 galaxy systems at 1 < z < 1.5 with deep photometry and extensive spectroscopy, ranging from groups to the most massive clusters. The groups are a subset of those identified from the deep X-ray and spectroscopic observations in the COSMOS and SXDF regions (Finoguenov et al 2010;Giodini et al 2012;Leauthaud et al 2012;Gozaliasl et al 2019).…”