Thursday, November 10, 2011

1111.2135 (Lihwai Lin et al.)

Clustering properties of BzK-selected galaxies in GOODS-N: environmental quenching and triggering of star formation at z ~ 2    [PDF]

Lihwai Lin, Mark Dickinson, Hung-Yu Jian, A. I. Merson, C. M. Baugh, Douglas Scott, Sebastien Foucaud, Wei-Hao Wang, Chi-Hung Yan, Hao-Jing Yan, Yi-Wen Cheng, Yicheng Guo, John Helly, Franz Kirsten, David C. Koo, Claudia del P. Lagos, Nicole Meger, Alexandra Pope, Luc Simard, Norman A. Grogin, Hugo Messias, Shiang-Yu Wang
Using a sample of $\textit{BzK}$-selected galaxies at $z \sim 2$ 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 (\sm), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (\textit{sBzK}s), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFR $\propto$ \sm$^{\alpha}$ with $\alpha = 0.74\pm0.20$, indicating a weak dependence on the stellar mass of the star formation rate efficiency. We also measure the angular correlation function and hence infer the correlation length for \textit{sBzK} galaxies as a function of \sm, SFR, and SSFR, as well as $K$-band apparent magnitude. We show that passive galaxies (\textit{pBzK}s) are more strongly clustered than \textit{sBzK} galaxies at a given stellar mass. We also find that the correlation length of \textit{sBzK} galaxies ranges from 4 to 17 \mpc, being a strong function of $M_{K}$, \sm, and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at $2\times 10^{-9}$ yr$^{-1}$, which is the typical value for ``main sequence'' star-forming galaxies at $z \sim 2$. 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: stronger clustering for relatively quiescent galaxies implies that the environment has started playing a role in quenching or reducing star formation at $z \sim 2$, while the interpretation for galaxies with elevated SSFRs (``starbursts'') might be attributed to galaxy mergers and/or other mechanisms which are also associated with dense environments.
View original: http://arxiv.org/abs/1111.2135

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