Conditional Quenching: A detailed look at the SFR-Density Relation at z ~ 0.9 from ORELSE

Abstract

We present a study of the star-formation rate (SFR)-density relation at z ~ 0.9 using data drawn from the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey. We find that SFR does depend on environment, but only for intermediate-stellar mass galaxies (10^10.1 < M* / Msol < 10^10.8) wherein the median SFR at the highest densities is 0.2-0.3 dex less than at lower densities at a significance of 4 sigma. Interestingly, mass does not drive SFR; galaxies that are more/less massive have SFRs that vary at most by ~20% across all environments showing no statistically significant dependence. We further split galaxies into low-redshift (z ~ 0.8) and high-redshift (z ~ 1.05) subsamples and observe nearly identical behavior. We devise a simple toy model to explore possible star-formation histories (SFHs) for galaxies evolving between these redshifts. The key assumption in this model is that star-forming galaxies in a given environment-stellar mass bin can be described as a superposition of two exponential timescales (SFR ~ e^(-t/tau)): a long-tau timescale with tau = 4 Gyr to simulate "normal" star-forming galaxies, and a short-tau timescale with free tau (between 0.3 < tau/Gyr < 2) to simulate galaxies on a quenching trajectory. In general we find that galaxies residing in low/high environmental densities are more heavily weighted to the long-tau/short-tau pathways respectively, which we argue is a signature of environmental quenching. Furthermore, for intermediate-stellar mass galaxies this transition begins at intermediate-density environments suggesting that environmental quenching is relevant in group-like halos and/or cluster infall regions.

17 pages, 7 figures

References in corpus (30)

• Cosmic Star Formation History
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• EAZY: A Fast, Public Photometric Redshift Code
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• Detection of quiescent galaxies in a bicolor sequence from z=0-2
• The effect of galaxy mass ratio on merger--driven starbursts
• What do we learn from IRAC observations of galaxies at 2 < z < 3.5?
• The DEEP2 Galaxy Redshift Survey: The Role of Galaxy Environment in the Cosmic Star-Formation History
• LoCuSS: The slow quenching of star formation in cluster galaxies and the need for pre-processing
• The Redshift Evolution of Wet, Dry, and Mixed Galaxy Mergers from Close Galaxy Pairs in the DEEP2 Galaxy Redshift Survey
• The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to far-infrared catalogs, medium-bandwidth photometric redshifts with improved accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5
• The environments of starburst and post-starburst galaxies at z=0.4-0.8
• A Comparative Study of Density Field Estimation for Galaxies: New Insights into the Evolution of Galaxies with Environment in COSMOS out to z~3
• How to quench a galaxy
• The Observations of Redshift Evolution in Large Scale Environments (ORELSE) Survey : I. The Survey Design and First Results on Cl 0023+0423 at z = 0.84 and RX J1821.6+6827 at z = 0.82
• Evidence for strong evolution in galaxy environmental quenching efficiency between z = 1.6 and z = 0.9
• Reconciling the observed star-forming sequence with the observed stellar mass function
• The DEEP2 Galaxy Redshift Survey: Environments of Poststarburst Galaxies at z~0.1 and z~0.8
• The reversal of the SF-density relation in a massive, X-ray selected galaxy cluster at z=1.58: results from Herschel
• The Complex Structure of the Cl 1604 Supercluster at z~0.9
• The pre-processing of subhaloes in SDSS groups and clusters
• The NOAO Fundamental Plane Survey - III. Variations in the stellar populations of red-sequence galaxies from the cluster core to the virial radius
• Glimpsing the Imprint of Local Environment on the Galaxy Stellar Mass Function
• What triggers galaxy transformations? The environments of post-starburst galaxies
• Serendipitous Discovery of an Overdensity of Lyman-Alpha Emitters at z~4.8 in the Cl1604 Supercluster Field
• The Environmental Dependence of Properties of Galaxies around the RDCSJ0910+54 Cluster at z=1.1
• The Properties of Radio Galaxies and the Effect of Environment in Large Scale Structures at $z\sim 1$
• The Evolutionary Sequence of Post-Starburst Galaxies
• X-Ray Emitting Active Galactic Nuclei from z = 0.6-1.3 in the Intermediate and High-Density Environments of the ORELSE Survey

Cited by in corpus (6)

• The VLA-COSMOS 3 GHz Large Project: Evolution of specific star formation rates out to $z\sim 5$
• The GOGREEN Survey: A deep stellar mass function of cluster galaxies at 1.0<z<1.4 and the complex nature of satellite quenching
• Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SClA2142 cocoon
• VIS3COS: III. environmental effects on the star formation histories of galaxies at z~0.8 seen in [OII], H$\delta$, and Dn4000
• A semi-analytical perspective on massive galaxies at $z\sim 0.55$
• Environmental impact on star-forming galaxies in a $z\sim 0.9$ cluster during course of galaxy accretion