CLUSTERING OF EXTREMELY RED OBJECTS IN THE SUBARU GTO 2DEG2 FIELD

Abstract

We study the angular correlation function of bright (<TEX>$K_s{\leq}19.5$</TEX>) Extremely Red Objects (EROs) selected in the Subaru GTO 2<TEX>$deg^2$</TEX> field. By applying the color selection criteria of <TEX>$R-K_s$</TEX> > 5.0, 5.5, and 6.0, we identify 9055, 4270, and 1777 EROs, respectively. The number density is consistent with similar studies on the optical - NIR color selected red galaxies. The angular correlation functions are derived for EROs with different limiting magnitude and different <TEX>$R-K_s$</TEX> color cut. When we assume that the angular correlation function <TEX>$w({\theta})$</TEX> follows a form of a power-law (i.e., <TEX>$w({\theta})=A{\theta}^{-{\delta}}$</TEX>), the value of the amplitude A was larger for brighter EROs compared to the fainter EROs. The result suggests that the brighter, thus more massive high-redshift galaxies, are clustered more strongly compared to the less massive galaxies. Assuming that EROs have redshift distribution centered at <z> ~ 1.1 with <TEX>${\sigma}_z=0.15$</TEX>, the spatial correlation length <TEX>$r_0$</TEX> of the EROs estimated from the observed angular correlation function ranges <TEX>${\sim}6-10h^{-1}Mpc$</TEX>. A comparison with the clustering of dark matter halos in numerical simulation suggests that the EROs are located in most massive dark matter halos and could be progenitors of <TEX>$L_{\ast}$</TEX> elliptical galaxies.