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

Abstract

We present results on the environmental dependence of the star-forming galaxy main sequence in 11 galaxy cluster fields at 1.0 < z < 1.5 from the Gemini Observations of Galaxies in Rich Early Environments Survey (GOGREEN) survey. We use a homogeneously selected sample of field and cluster galaxies whose membership is derived from dynamical analysis. Using [O ii]-derived star formation rates (SFRs), we find that cluster galaxies have suppressed SFRs at fixed stellar mass in comparison to their field counterparts by a factor of 1.4 ± 0.1 (∼ 3.3σ) across the stellar mass range: 9.0 < log(M * /M ) < 11.2. We also find that this modest suppression in the cluster galaxy star-forming main sequence is mass and redshift dependent: the difference between cluster and field increases towards lower stellar masses and lower redshift. When comparing the distribution of cluster and field galaxy SFRs to the star-forming main sequence, we find an overall shift towards lower SFRs in the cluster population, and note the absence of a tail of high SFR galaxies as seen in the field. Given this observed suppression in the cluster galaxy star-forming main sequence, we explore the implications for several scenarios such as formation time differences between cluster and field galaxies, and environmentally-induced star formation quenching and associated timescales.

The GOGREEN survey: post-infall environmental quenching fails to predict the observed age difference between quiescent field and cluster galaxies at z &gt; 1

“…Comparing the star formation timescales between galaxies in clusters and field environments, we test simple quenching models which have been proposed to explain the difference in ages between the two populations. This work complements the comparison of the stellar mass distributions measured in (van der Burg et al 2020), and the relation between stellar mass and star formation for star-forming galaxies (Old et al 2020). Table 1.…”

“…This comparison is discussed in Appendix C. We note that the stellar masses reported in other GOGREEN papers (e.g. Balogh et al 2017;Chan et al 2019;Old et al 2020;van der Burg et al 2020) are derived using FAST, and therefore differ from the stellar masses in this paper by +0.2 dex. Since the focus of this paper is a differential comparison between galaxies in cluster and field environments, our results are less sensitive to the systematic effects related to model choices.…”

“…Peng et al 2010;Muzzin et al 2012) or modest (e.g. Vulcani et al 2010;Popesso et al 2011;Koyama et al 2013;Old et al 2020, andMcGee et al 2011 for groups) trends between the star forming main sequence and environment.…”

“…The SXDF galaxies are marked as yellow diamonds in Figure C1 as their fiducial masses were not derived from FAST but from similar template fitting with Bruzual & Charlot (2003) models described in Mehta et al (2018). The stellar masses used in Old et al (2020) and van der Burg et al (2020), as well as in the upcoming data release (Balogh et al 2020, in prep) are based on FAST masses, and therefore will differ from the stellar masses in this paper.…”

MUSE Analysis of Gas around Galaxies (MAGG) – II: metal-enriched halo gas around z ∼ 1 galaxies

“…The environmental dependence of galaxy properties has been observed out to higher redshifts (z ∼ 1.5) as well (Peng et al 2010;Wetzel et al 2012;Balogh et al 2016;Lemaux et al 2019;Old et al 2020), though the relative importance of different physical mechanisms in removing gas from galaxies in groups is still uncertain at z ∼ 1. However, it is likely that the one or more processes in the group environment causes the CGM to be perturbed and metals to be dislodged further out, leading to enhancement in the Mg II absorption cross-section.…”