The VIMOS Public Extragalactic Redshift Survey (VIPERS)

Star formation history of passive red galaxies^⋆

¹ Center for Theoretical Physics, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
² National Center for Nuclear Research, ul. A. Soltana 7, 05-400 Otwock, Poland
³ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Bassini 15, 20133 Milano, Italy
⁴ Astronomical Observatory of the Jagiellonian University, Orla 171, 30-001 Cracow, Poland
⁵ INAF–Osservatorio Astronomico di Brera, via Brera 28, 20122 Milano, via E. Bianchi 46, 23807 Merate, Italy
⁶ INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁷ Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁸ Dipartimento di Fisica, Università di Milano-Bicocca, P.zza della Scienza 3, 20126 Milano, Italy
⁹ INAF–Osservatorio Astronomico di Torino, 10025 Pino Torinese, Italy
¹⁰ Laboratoire Lagrange, UMR7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France
¹¹ INAF–Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
¹² Institute of Physics, Jan Kochanowski University, ul. Swietokrzyska 15, 25-406 Kielce, Poland
¹³ Dipartimento di Fisica e Astronomia – Alma Mater Studiorum Università di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
¹⁴ INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
¹⁵ IRAP, 9 av. du colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹⁶ Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Burnaby Road, Portsmouth, PO1 3FX, 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 Aix Marseille Université, CNRS, CPT, UMR 7332, 13288 Marseille, France
²⁰ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
²¹ INFN, Sezione di Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
²² INAF–Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone (RM), Italy
²³ Division of Particle and Astrophysical Science,Nagoya University, Furo-cho, Chikusa-ku, 464-8602 Nagoya, Japan

^⋆⋆ Corresponding author: M. Siudek, e-mail: gsiudek@cft.edu.pl

Received: 17 May 2016
Accepted: 2 November 2016

Abstract

Aims. We trace the evolution and the star formation history of passive red galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). The detailed spectral analysis of stellar populations of intermediate-redshift passive red galaxies allows the build up of their stellar content to be followed over the last 8 billion years.

Methods. We extracted a sample of passive red galaxies in the redshift range 0.4 <z< 1.0 and stellar mass range 10 < log (M_star/M_⊙) < 12 from the VIPERS survey. The sample was selected using an evolving cut in the rest-frame U−V color distribution and additional cuts that ensured high quality. The spectra of passive red galaxies were stacked in narrow bins of stellar mass and redshift. We use the stacked spectra to measure the 4000 Å break (D4000) and the Hδ Lick index (Hδ_A) with high precision. These spectral features are used as indicators of the star formation history of passive red galaxies. We compare the results with a grid of synthetic spectra to constrain the star formation epochs of these galaxies. We characterize the formation redshift-stellar mass relation for intermediate-redshift passive red galaxies.

Results. We find that at z ~ 1 stellar populations in low-mass passive red galaxies are younger than in high-mass passive red galaxies, similar to what is observed at the present epoch. Over the full analyzed redshift range 0.4 < z < 1.0 and stellar mass range 10 < log (M_star/M_⊙) < 12, the D4000 index increases with redshift, while Hδ_A gets lower. This implies that the stellar populations are getting older with increasing stellar mass. Comparison to the spectra of passive red galaxies in the SDSS survey (z ~ 0.2) shows that the shape of the relations of D4000 and Hδ_A with stellar mass has not changed significantly with redshift. Assuming a single burst formation, this implies that high-mass passive red galaxies formed their stars at z_form ~ 1.7, while low-mass galaxies formed their main stellar populations more recently, at z_form ~ 1. The consistency of these results, which were obtained using two independent estimators of the formation redshift (D4000 and Hδ_A), further strengthens a scenario in which star formation proceeds from higher to lower mass systems as time passes, i.e., what has become known as the downsizing picture.