The VIMOS Public Extragalactic Redshift Survey (VIPERS)

Downsizing of the blue cloud and the influence of galaxy size on mass quenching over the last eight billion years^⋆

¹ INAF–Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, via. E. Bianchi 46, 23807 Merate, Italy
e-mail: chris.haines@oa-brera.inaf.it
² Institute of Physics, Jan Kochanowski University, ul. Swietokrzyska 15, 25-406 Kielce, Poland
³ Università degli Studi di Milano, via G. Celoria 16, 20133 Milano, Italy
⁴ Aix-Marseille Univ., CNRS, LAM, Laboratoire d’Astrophysique de Marseille, 13388 Marseille, France
⁵ INAF–Osservatorio Astronomico di Bologna, via Gobetti 93/3, 40129 Bologna, Italy
⁶ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Bassini 15, 20133 Milano, Italy
⁷ INAF–Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
⁸ INAF–Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy
⁹ Dipartimento di Fisica e Astronomia – Alma Mater Studiorum Università di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
¹⁰ Laboratoire Lagrange, UMR 7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France
¹¹ National Centre for Nuclear Research, ul. Hoza 69, 00-681 Warszawa, Poland
¹² INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
¹³ Aix-Marseille Université, Jardin du Pharo, 58 bd Charles Livon, 13284 Marseille Cedex 7, France
¹⁴ IRAP, 9 Av. du colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹⁵ Astronomical Observatory of the Jagiellonian University, Orla 171, 30-001 Cracow, Poland
¹⁶ School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
¹⁷ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica Bologna, via Gobetti 101, 40129 Bologna, Italy
¹⁸ INAF – Istituto di Radioastronomia, via Gobetti 101, 40129, Bologna, Italy
¹⁹ Canada-France-Hawaii Telescope, 65–1238 Mamalahoa Highway, Kamuela, HI 96743, USA
²⁰ Aix-Marseille Univ., Univ. Toulon, CNRS, CPT, 13013 Marseille, France
²¹ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
²² INFN, Sezione di Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
²³ INAF–Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone (RM), Italy
²⁴ Astronomical Observatory of the University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland
²⁵ Department of Astronomy & Physics, Saint Mary’s University, 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
²⁶ Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
²⁷ Center for Theoretical Physics, Al. Lotnikow 32/46, 02-668 Warsaw, Poland

Received: 22 November 2016
Accepted: 28 March 2017

Abstract

We use the full VIPERS redshift survey in combination with SDSS-DR7 to explore the relationships between star-formation history (using d4000), stellar mass and galaxy structure, and how these relationships have evolved since z ~ 1. We trace the extents and evolutions of both the blue cloud and red sequence by fitting double Gaussians to the d4000 distribution of galaxies in narrow stellar mass bins, for four redshift intervals over 0 <z< 1. This reveals downsizing in star formation, since the high-mass limit of the blue cloud has retreated steadily with time from ℳ ~ 10^11.2 M_⊙at z ~ 0.9 to ℳ ~ 10^10.7 M_⊙by the present day. The number density of massive blue-cloud galaxies (ℳ > 10¹¹M_⊙, d4000 < 1.55) drops sharply by a factor five between z ~ 0.8 and z ~ 0.5. These galaxies are becoming quiescent at a rate that largely matches the increase in the numbers of massive passive galaxies seen over this period. We examine the size-mass relation of blue-cloud galaxies, finding that its high-mass boundary runs along lines of constant ℳ /r_eor equivalently inferred velocity dispersion. Larger galaxies can continue to form stars to higher stellar masses than smaller galaxies. As blue-cloud galaxies approach this high-mass limit, entering a narrow diagonal region within the size-mass plane termed the “quenching zone”, they start to be quenched, their d4000 values increasing to push them towards the green valley. In parallel, their structures change, showing higher Sérsic indices and central stellar mass densities. For these galaxies, bulge growth is required for them to reach the high-mass limit of the blue cloud and be quenched by internal mechanisms. The blue-cloud galaxies that are being quenched at z ~ 0.8 lie along the same size-mass relation as present day quiescent galaxies and seem the likely progenitors of today’s S0s.