Gemini Observations of Galaxies in Rich Early Environments (GOGREEN) I: survey description

Abstract

We describe a new Large Program in progress on the Gemini North and South telescopes: Gemini Observations of Galaxies in Rich Early Environments (GOGREEN). This is an imaging and deep spectroscopic survey of 21 galaxy systems at 1 < z < 1.5, selected to span a factor >10 in halo mass. The scientific objectives include measuring the role of environment in the evolution of low-mass galaxies, and measuring the dynamics and stellar contents of their host haloes. The targets are selected from the SpARCS, SPT, COSMOS, and SXDS surveys, to be the evolutionary counterparts of today's clusters and groups. The new red-sensitive Hamamatsu detectors on GMOS, coupled with the nod-and-shuffle sky subtraction, allow simultaneous wavelength coverage over λ ∼ 0.6-1.05 µm, and this enables a homogeneous and statistically complete redshift survey of galaxies of all types. The spectroscopic sample targets galaxies with AB magnitudes z < 24.25 and [3.6] µm < 22.5, and is therefore statistically complete for stellar masses M * 10 10.3 M , for all galaxy types and over the entire redshift range. Deep, multiwavelength imaging has been acquired over larger fields for most systems, spanning u through K, in addition to deep IRAC imaging at 3.6 µm. The spectroscopy is ∼50 per cent complete as of semester 17A, and we anticipate a final sample of ∼500 new cluster members. Combined with existing spectroscopy on the brighter galaxies from GCLASS, SPT, and other sources, GOGREEN will be a large legacy cluster and field galaxy sample at this redshift that spectroscopically covers a wide range in stellar mass, halo mass, and clustercentric radius.

The GOGREEN survey: the environmental dependence of the star-forming galaxy main sequence at 1.0 &lt; z &lt; 1.5

“…This table summarises the key properties of the eleven clusters used in this study that are targeted by the GOGREEN survey. z c is the initial cluster mean redshift estimate, taken from Balogh et al (2017), with the exception of SpARCS0219, for which the z c estimates have been obtained using the peak of the z distribution. N tot is the number of objects with good quality redshifts in the cluster field from either GOGREEN or the literature, avoiding double entries, and N mem is the number of galaxies that are considered as members by at least one of the two C.L.U.M.P.S and Clean algorithms.…”

“…The goal of this study is to measure the difference in the star-forming galaxy main sequence between cluster and field galaxies with a deep spectroscopic sample of homogeneously targeted galaxies above z > 1. For this purpose, we use the recently completed Gemini Observations of Galaxies in Rich Early ENvironments (GOGREEN) survey (Balogh et al 2017). In Section 2, we describe the key survey details including the cluster sample and some aspects of the data reduction.…”

The Rest-frame H-band Luminosity Function of Red-sequence Galaxies in Clusters at 1.0 < z < 1.3

“…Combining all of the available redshifts on these overdensities, by the end of the survey we expect to have a statistically complete sample down to stellar masses of M * 10 10.3 M e for all galaxy types. The design of the survey and the science objectives, as well as the data reduction, are described in detail in Balogh et al (2017).…”

Semi-analytic galaxies – II. Revealing the role of environmental and mass quenching in galaxy formation

“…At fixed stellar mass, the star formation rate density (SFRD) declines with decreasing redshift more abruptly for galaxies in clusters than in the field (Guglielmo et al 2015), highlighting the importance of environmental quenching, especially since z ∼ 1.5 (Nantais et al 2017). On-going programmes like GOGREEN (Gemini Observations of Galaxies in Rich Early Environments) will contribute towards determining the role of environment in the evolution of low-mass galaxies (Balogh et al 2017).…”