We study the angular correlation function of bright (Ks ≤ 19.5) Extremely Red Objects (EROs) selected in the Subaru GTO 2 deg2 field. By applying the color selection criteria of R − Ks > 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 R −Ks color cut. When we assume that the angular correlation function w() follows a form of a power-law (i.e., w() = A−), 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 hzi ∼ 1.1 with z = 0.15, the spatial correlation length r0 of the EROs estimated from the observed angular correlation function ranges ∼ 6-10 h−1Mpc. 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 L∗ elliptical galaxies.

Abstract
1. INTRODUCTION
2. DATA
    2.1. Optical and Near-infrared Data in the SubaruGTO 2 deg2 Field
    2.2. The ERO Sample
3. TWO-POINT ANGULAR CORRELATION FUNCTION
    3.1. Method
    3.2. Result
4. DISCUSSION
    4.1. Spatial Clustering
    4.2. Mass of Dark Matter Halos Hosting EROs
5. SUMMARY
REFERENCES

• Jihey Shin(Department of Astronomy and Atmospheric Sciences, Kyungpook National University)
• Hyunjin Shim(Department of Earth Science Education, Kyungpook National University) Corresponding author
• Ho Seong Hwang(Quantum Universe Center, Korea Institute for Advanced Study)
• Jongwan Ko(Korea Astronomy and Space Science Institute/University of Science and Technology)
• Jong Chul Lee(Korea Astronomy and Space Science Institute)
• Yousuke Utsumi(Hiroshima Astrophysical Science Center, Hiroshima University)
• Narae Hwang(Korea Astronomy and Space Science Institute)
• Byeong-Gon Park(Korea Astronomy and Space Science Institute)