The VIMOS Public Extragalactic Redshift Survey (VIPERS)

The decline of cosmic star formation: quenching, mass, and environment connections^⋆

¹ INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
² Dipartimento di Fisica e Astronomia – Alma Mater Studiorum Università di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
³ Aix Marseille Univ, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, 13013 Marseille, France
⁴ INAF–Osservatorio Astronomico di Brera, via Brera 28, 20122 Milano – via E. Bianchi 46, 23807 Merate, Italy
⁵ Università degli Studi di Milano, via G. Celoria 16, 20133 Milano, Italy
⁶ INAF–Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
⁷ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁸ INFN, Sezione di Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁹ INAF–Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone (RM), Italy
¹⁰ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Bassini 15, 20133 Milano, Italy
¹¹ INAF–Osservatorio Astrofisico di Torino, 10025 Pino Torinese, Italy
¹² Laboratoire Lagrange, UMR7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France
¹³ Institute of Physics, Jan Kochanowski University, ul. Swietokrzyska 15, 25-406 Kielce, Poland
¹⁴ National Centre for Nuclear Research, ul. Hoza 69, 00-681 Warszawa, Poland
¹⁵ INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
¹⁶ Department of Astronomy & Physics, Saint Mary’s University, 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
¹⁷ Aix-Marseille Universite, Jardin du Pharo, 58 bd Charles Livon, 13284 Marseille Cedex 7, France
¹⁸ IRAP, 9 Av. du Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹⁹ Astronomical Observatory of the Jagiellonian University, Orla 171, 30-001 Cracow, Poland
²⁰ School of Physics and Astronomy, University of St Andrews, St. Andrews KY16 9SS, UK
²¹ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Bologna, via Gobetti 101, 40129 Bologna, Italy
²² INAF–Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
²³ Aix Marseille Univ., Univ. Toulon,CNRS, CPT, 13284 Marseille, France
²⁴ Univ. Lyon, Univ. Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon, UMR 5574, 69230 Saint-Genis-Laval, France
²⁵ Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland
²⁶ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

^⋆⋆ Corresponding author: O. Cucciati, olga.cucciati@oabo.inaf.it

Received: 22 November 2016
Accepted: 25 January 2017

Abstract

We use the final data of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to investigate the effect of the environment on the evolution of galaxies between z = 0.5 and z = 0.9. We characterise local environment in terms of the density contrast smoothed over a cylindrical kernel, the scale of which is defined by the distance to the fifth nearest neighbour. This is performed by using a volume-limited sub-sample of galaxies complete up to z = 0.9, but allows us to attach a value of local density to all galaxies in the full VIPERS magnitude-limited sample to i < 22.5. We use this information to estimate how the distribution of galaxy stellar masses depends on environment. More massive galaxies tend to reside in higher-density environments over the full redshift range explored. Defining star-forming and passive galaxies through their (NUV−r) vs. (r−K) colours, we then quantify the fraction of star-forming over passive galaxies, f_ap, as a function of environment at fixed stellar mass. f_ap is higher in low-density regions for galaxies with masses ranging from log (ℳ/ℳ_⊙) = 10.38 (the lowest value explored) to at least log (ℳ/ℳ_⊙) ~ 11.3, although with decreasing significance going from lower to higher masses. This is the first time that environmental effects on high-mass galaxies are clearly detected at redshifts as high as z ~ 0.9. We compared these results to VIPERS-like galaxy mock catalogues based on a widely used galaxy formation model. The model correctly reproduces f_ap in low-density environments, but underpredicts it at high densities. The discrepancy is particularly strong for the lowest-mass bins. We find that this discrepancy is driven by an excess of low-mass passive satellite galaxies in the model. In high-density regions, we obtain a better (although not perfect) agreement of the model f_ap with observations by studying the accretion history of these model galaxies (that is, the times when they become satellites), by assuming either that a non-negligible fraction of satellites is destroyed, or that their quenching timescale is longer than ~ 2 Gyr.