Comparison of the VIMOS-VLT Deep Survey with the Munich semi-analytical model

I. Magnitude counts, redshift distribution, colour bimodality, and galaxy clustering^⋆

¹ INAF – Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy
e-mail: sylvain.delatorre@brera.inaf.it
² INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, via Bassini 15, 20133 Milano, Italy
³ Max Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching bei München, Germany
⁴ Universitätssternwarte München, Scheinerstrasse 1, 81679 München, Germany
⁵ INAF – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy
⁶ Centre de Recherche Astrophysique de Lyon, UMR 5574, Université Claude Bernard Lyon-École Normale Supérieure de Lyon-CNRS, 69230 Saint-Genis Laval, France
⁷ Laboratoire d’Astrophysique de Marseille, UMR 6110, CNRS-Université de Provence, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
⁸ Institut d’Astrophysique de Paris, UMR 7095, Université Pierre et Marie Curie, 98bis Bd. Arago, 75014 Paris, France
⁹ The Andrzej Soltan Institute for Nuclear Studies, ul. Hoza 69, 00-681 Warszawa, Poland
¹⁰ Astronomical Observatory of the Jagiellonian University, ul Orla 171, 30-244, Kraków, Poland
¹¹ INAF – Osservatorio Astronomico di Torino, strada Osservatorio 20, 10025 Pino Torinese, Italy
¹² IRA-INAF, via Gobetti 101, 40129 Bologna, Italy
¹³ Canada France Hawaii Telescope corporation, Mamalahoa Hwy, Kamuela, HI-96743, USA
¹⁴ INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
¹⁵ Laboratoire d’Astrophysique de Toulouse-Tarbes, UMR 5572, CNRS-Université de Toulouse, 14 Av. E. Belin, 31400 Toulouse, France
¹⁶ Department of Earth Sciences, National Taiwan Normal University, 88 Tingzhou Road, Sec. 4, Taipei 11677, Taiwan, PR China
¹⁷ Departamento de Ciencias Fisicas, Facultad de Ingenieria, Universidad Andres Bello, Santiago, Chile
¹⁸ Centre de Physique Théorique, UMR 6207, CNRS-Université de Provence, 13288 Marseille, France
¹⁹ ISDC, Geneva Observatory, University of Geneva, Ch. d’Ècogia 16, 1290 Versoix, Switzerland

Received: 6 August 2010
Accepted: 2 October 2010

Abstract

Aims. This paper presents a detailed comparison between high-redshift observations from the VIMOS-VLT Deep Survey (VVDS) and predictions from the Munich semi-analytical model of galaxy formation. In particular, we focus this analysis on the magnitude, redshift, and colour distributions of galaxies, as well as their clustering properties.

Methods. We constructed 100 quasi-independent mock catalogues, using the output of the semi-analytical model presented in De Lucia & Blaizot (2007, MNRAS, 375, 2). We then applied the same observational selection function of the VVDS-Deep survey, so as to carry out a fair comparison between models and observations.

Results. We find that the semi-analytical model reproduces well the magnitude counts in the optical bands. It tends, however, to overpredict the abundance of faint red galaxies, in particular in the i′ and z′ bands. Model galaxies exhibit a colour bimodality that is only in qualitative agreement with the data. In particular, we find that the model tends to overpredict the number of red galaxies at low redshift and of blue galaxies at all redshifts probed by VVDS-Deep observations, although a large fraction of the bluest observed galaxies is absent from the model. In addition, the model overpredicts by about 14 per cent the number of galaxies observed at 0.2 < z < 1 with I_AB < 24. When comparing the galaxy clustering properties, we find that model galaxies are more strongly clustered than observed ones at all redshift from z = 0.2 to z = 2, with the difference being less significant above z ≃ 1. When splitting the samples into red and blue galaxies, we find that the observed clustering of blue galaxies is well reproduced by the model, while red model galaxies are much more clustered than observed ones, being principally responsible for the strong global clustering found in the model.

Conclusions. Our results show that the discrepancies between Munich semi-analytical model predictions and VVDS-Deep observations, particularly in the galaxy colour distribution and clustering, can be explained to a large extend by an overabundance of satellite galaxies, mostly located in the red peak of the colour bimodality predicted by the model.