Clustering, host halos, and environment of z ~ 2 galaxies as a function of their physical properties

¹ Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu – CNRS – Université Paris Diderot, CEA-Saclay, pt courrier 131, 91191 Gif-sur-Yvette, France
e-mail: matthieu.bethermin@laposte.net
² European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
matthieu.bethermin@eso.org
³ Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, 00014 Helsinki, Finland
⁴ Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98 bis boulevard Arago, 75014 Paris, France
⁵ Dipartimento di Astronomia, Universita di Padova, Vicolo dell’Osservatorio 3, Padova 35122, Italy
⁶ National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson AZ 85719, USA
⁷ Computational Cosmology, Department of Physics, University of Durham, South Road, Durham, DH1 3LE, UK
⁸ MPE, Postfach 1312, 85741 Garching, Germany
⁹ Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA

Received: 17 January 2014
Accepted: 27 April 2014

Abstract

Using a sample of 25 683 star-forming and 2821 passive galaxies at z ~ 2, selected in the COSMOS field following the BzK color criterion, we study the hosting halo mass and environment of galaxies as a function of their physical properties. Spitzer and Herschel allow us to obtain accurate star formation rate estimates for starburst galaxies. We measure the autocorrelation and cross-correlation functions of various galaxy subsamples and infer the properties of their hosting halos using both a halo occupation model and the linear bias at large scale. We find that passive and star-forming galaxies obey a similarly rising relation between the halo and stellar mass. The mean host halo mass of star-forming galaxies increases with the star formation rate between 30 M_⊙ yr^-1 and 200 M_⊙ yr^-1, but flattens for higher values, except if we select only main-sequence galaxies. This reflects the expected transition from a regime of secular coevolution of the halos and the galaxies to a regime of episodic starburst. We find similar large-scale biases for main-sequence, passive, and starburst galaxies at equal stellar mass, suggesting that these populations live in halos of the same mass. However, we detect an excess of clustering on small scales for passive galaxies and showed, by measuring the large-scale bias of close pairs of passive galaxies, that this excess is caused by a small fraction (~16%) of passive galaxies being hosted by massive halos (~3 × 10¹³ M_⊙) as satellites. Finally, extrapolating the growth of halos hosting the z ~ 2 population, we show that M_⋆ ~ 10¹⁰ M_⊙ galaxies at z ~ 2 will evolve, on average, into massive (M_⋆ ~ 10¹¹ M_⊙), field galaxies in the local Universe and M_⋆ ~ 10¹¹ M_⊙ galaxies at z = 2 into local, massive, group galaxies. We also identify two z ~ 2 populations which should end up in today’s clusters: massive (>M_⋆ ~ 10¹¹ M_⊙), strongly star-forming ( > 200 M_⊙ yr^-1), main-sequence galaxies, and close pairs of massive, passive galaxies.