Mon. Not. R. Astron. Soc., 484, 4695-4710 (2019/April-3)
Conditional quenching: a detailed look at the SFR-density relation at z ∼ 0.9 from ORELSE.
TOMCZAK A.R., LEMAUX B.C., LUBIN L.M., PELLICCIA D., SHEN L., GAL R.R., HUNG D., KOCEVSKI D.D., LE FEVRE O., MEI S., RUMBAUGH N., SQUIRES G.K. and WU P.-F.
Abstract (from CDS):
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 (1010.1 < M*/M☉ < 1010.8) wherein the median SFR at the highest densities is 0.2-0.3 dex less than at lower densities at a significance of 4σ. Galaxies that are more/less massive than this have SFRs that vary at most by ~20 per cent across all environments, but show no statistically significant trend. We further split galaxies into low-redshift (z ∼ 0.8) and high-redshift (z ∼ 1.05) subsamples and observe nearly identical behaviour. We devise a simple toy model to explore possible star formation histories 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 time-scales (SFR ∝ e–t/τ): a long-τ time-scale with τ = 4 Gyr to simulate 'normal' star-forming galaxies, and a short-τ time-scale with free τ (between 0.3 <= τ/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-τ/short-τ 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 haloes and/or cluster infall regions.
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
techniques: photometric - techniques: spectroscopic - galaxies: clusters: general - galaxies: evolution - galaxies: groups: general
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