CLUSTERING PROPERTIES OF BzK-SELECTED GALAXIES IN GOODS-N: ENVIRONMENTAL QUENCHING AND TRIGGERING OF STAR FORMATION ATz∼ 2

Abstract

Using a sample of BzK-selected galaxies at z ∼ 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellar mass (M * ), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFR ∝ M * α with α = 0.74 ± 0.20 down to M * ∼ 10 9 M ⊙ , indicating a weak dependence on the stellar mass of the star formation rate efficiency, namely, SSFR. We also measure the angular correlation function and hence infer the correlation length for sBzK galaxies as a function of M * , SFR, and SSFR, as well as K-band apparent magnitude. We show that passive galaxies (pBzKs) are more strongly clustered than sBzK galaxies at a given stellar mass, mirroring the color−density relation seen at lower redshifts. We also find that the correlation length of sBzK galaxies ranges from 4 to 20 h −1 Mpc, being a strong function of M K , M * , and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at 2 × 10 −9 yr −1 , which is the typical value for "main sequence" starforming galaxies at z ∼ 2. We show that the correlation length reaches a minimum at this characteristic value, and is larger for galaxies with both smaller and larger SSFRs; a dichotomy that is only marginally implied from the predictions of the semi-analytical models. Our results suggest that there are two types of environmental effects at work at z ∼ 2. Stronger clustering for relatively quiescent galaxies implies that the environment has started to play a role in quenching star formation. At the same time, stronger clustering for galaxies with elevated SSFRs ("starbursts") might be attributed to an increased efficiency for galaxy interactions and mergers in dense environments.

The interaction-driven starburst contribution to the cosmic star formation rate density

“…A similar mismatch between the observed SFRs and those expected by various kind of SAMs and hydrodynamical simulations has also been reported by several authors at z 2 (see e.g. Daddi et al 2007;Davé 2008;Fontanot et al 2009;Damen et al 2009;Santini et al 2009;Lin et al 2012). This discrepancy indicates either an incompleteness in our knowledge of galaxy assembly or systematic effects in stellar mass and/or SFR determinations, or both.…”

“…Daddi et al 2007;Davé 2008;Fontanot et al 2009;Damen et al 2009;Santini et al 2009;Lin et al 2012). Understanding whether this mismatch comes from systematic effects in the stellar mass and/or SFR determinations, or from the incompleteness in our basic picture of galaxy assembly is a very difficult task.…”

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

“…This also justifies a posteriori the hypothesis of the same M − M h relation for both populations in the model of Béthermin et al (2013) linking dark matter halos and infrared galaxy populations. The correlation length is compatible with the prediction of the Lagos et al (2011) model, contrary to what was claimed by Lin et al (2012) because they used a very small scale signal for which the one-halo term could be in excess compared to the power-law approximation and because of possible problems of deblending. We also compared our M − M h relation with the results of estimates based on abundance matching (Behroozi et al 2010;Moster et al 2010;Béthermin et al 2012b) finding general agreement, except for the case of Wang et al (2013) who predicts larger halo mass for M > 10 11 M galaxies.…”

“…Lee et al (2009) studied the UV-light-to-halo-mass ratio at 3 < z < 5, and found a decrease of this ratio with time at fixed halo mass. Finally, Lin et al (2012) studied the clustering of z ∼ 2 galaxies as a function of SFR and sSFR, estimated using UV luminosity corrected for dust extinction, and found clustering increasing with the distance of galaxies from the main sequence (i.e., with sSFR). Finally, several studies using the correlated anisotropies of the cosmic infrared background (CIB), which is the relic emission of the dust emission from all star-forming galaxies across cosmic times, showed that from z = 0 to z = 3 the bulk of the star formation is hosted by halos of ∼10 12−13 M (e.g., Béthermin et al 2013;Viero et al 2013;Planck Collaboration XXX 2014).…”

The abundance and colours of galaxies in high-redshift clusters in the cold dark matter cosmology

“…Baldry et al 2004;Bell et al 2004;Brinchmann et al 2004), with many studies supporting a high formation redshift of the stellar population of z f 2 (e.g. Ellis et al 1997;Smail et al 1998;Stanford et al 1998;Ponman, Cannon & Navarro 1999;López-Cruz, Barkhouse & Yee 2004;Gladders & Yee 2005;Miller et al 2005;Voit 2005;Mei et al 2006aMei et al ,b, 2009Mei et al , 2012Koester et al 2007;Gilbank et al 2008Gilbank et al , 2011Lidman et al 2008;Wilson et al 2009;Lin et al 2012). There is, however, some observational evidence for ongoing star formation in clusters at z 1, (e.g.…”