The VIMOS Public Extragalactic Redshift Survey (VIPERS)^★

An unbiased estimate of the growth rate of structure at 〈z〉 = 0.85 using the clustering of luminous blue galaxies

¹ INAF–Osservatorio Astronomico di Brera, via Brera 28, 20122 Milano – via E. Bianchi 46, 23807 Merate, Italy
e-mail: faizan.mohammad@brera.inaf.it
² Dipartimento di Scienza e Alta Tecnologia, Università degli studi dell’Insubria, via Valleggio 11, 22100 Como, Italy
³ Università degli Studi di Milano, via G. Celoria 16, 20133 Milano, Italy
⁴ Aix-Marseille Univ., Université Toulon, CNRS, CPT, 13288 Marseille, France
⁵ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁶ INFN, Sezione di Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁷ INAF–Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone (RM), Italy
⁸ Aix-Marseille Univ., CNRS, LAM, Laboratoire d’Astrophysique de Marseille, 13388 Marseille, France
⁹ Dipartimento di Fisica e Astronomia, Alma Mater Studiorum Università di Bologna, via Gobetti 93/2, 40129 Bologna, Italy
¹⁰ INFN, Sezione di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy
¹¹ INAF–Osservatorio Astronomico di Bologna, via Gobetti 93/3, 40129 Bologna, Italy
¹² Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
¹³ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Bassini 15, 20133 Milano, Italy
¹⁴ INAF–Osservatorio Astrofisico di Torino, 10025 Pino Torinese, Italy
¹⁵ Laboratoire Lagrange, UMR},7293, Université de Nice Sophia Antipolis, CNRS, Observatoire de la Côte dAzur, 06300 Nice, France
¹⁶ Institute of Physics, Jan Kochanowski University, ul. Swietokrzyska 15, 25-406 Kielce, Poland
¹⁷ National Centre for Nuclear Research, ul. Hoza 69, 00-681 Warszawa, Poland
¹⁸ Aix-Marseille Universit, Jardin du Pharo, 58 bd Charles Livon, 13284 Marseille Cedex 7, France
¹⁹ IRAP, 9 Av. du colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
²⁰ Astronomical Observatory of the Jagiellonian University, Orla 171, 30-001 Cracow, Poland
²¹ School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
²² INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica Bologna, via Gobetti 101, 40129 Bologna, Italy
²³ INAF–Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
²⁴ Canada-France-Hawaii Telescope, 65–1238 Mamalahoa Highway, Kamuela, HI 96743, USA
²⁵ Department of Astronomy, University of Geneva, ch. dEcogia 16, 1290 Versoix, Switzerland
²⁶ INAF–Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
²⁷ Department of Astronomy & Physics, Saint Mary’s University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3, Canada

Received: 31 July 2017
Accepted: 5 October 2017

Abstract

We used the VIMOS Public Extragalactic Redshift Survey (VIPERS) final data release (PDR-2) to investigate the performance of colour-selected populations of galaxies as tracers of linear large-scale motions. We empirically selected volume-limited samples of blue and red galaxies as to minimise the systematic error on the estimate of the growth rate of structure fσ₈ from the anisotropy of the two-point correlation function. To this end, rather than rigidly splitting the sample into two colour classes we defined the red or blue fractional contribution of each object through a weight based on the (U − V) colour distribution. Using mock surveys that are designed to reproduce the observed properties of VIPERS galaxies, we find the systematic error in recovering the fiducial value of fσ₈ to be minimised when using a volume-limited sample of luminous blue galaxies. We modelled non-linear corrections via the Scoccimarro extension of the Kaiser model (with updated fitting formulae for the velocity power spectra), finding systematic errors on fσ₈ of below 1–2%, using scales as small as 5 h⁻¹ Mpc. We interpret this result as indicating that selection of luminous blue galaxies maximises the fraction that are central objects in their dark matter haloes; this in turn minimises the contribution to the measured ξ(r_p,π) from the 1-halo term, which is dominated by non-linear motions. The gain is inferior if one uses the full magnitude-limited sample of blue objects, consistent with the presence of a significant fraction of blue, fainter satellites dominated by non-streaming, orbital velocities. We measured a value of f σ₈ = 0.45 ± 0.11 over the single redshift range 0.6 ≤ z ≤ 1.0, corresponding to an effective redshift for the blue galaxies 〈z〉=0.85. Including in the likelihood the potential extra information contained in the blue-red galaxy cross-correlation function does not lead to an appreciable improvement in the error bars, while it increases the systematic error.