GOLDRUSH. III. A systematic search for protoclusters at z ∼ 4 based on the >100 deg2 area

PASJ: Publications of the Astronomical Society of Japan

Lee, Chien-Hsiu¹  Akiyama, Masayuki²  Tanaka, Masayuki²  Ouchi, Masami²  Goto, Tomotsugu²  Ono, Yoshiaki²  Lin, Yen-Ting³  Toshikawa, Jun⁴  Harikane, Yuichi⁴  Kodama, Tadayuki⁴  Matsuda, Yuichi⁴  Ishikawa, Shogo⁵  Kashikawa, Nobunari⁶  Uchiyama, Hisakazu⁶  Overzier, Roderik⁶  Komiyama, Yutaka⁶  Onoue, Masafusa⁶  Nagao, Tohru⁶ 

[1] Academia Sinica Institute of Astronomy and Astrophysics, PO Box 23-141, Taipei 10617, Taiwan;Department of Astronomical Science, Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan;Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582, Japan;Observatório Nacional, Rua José Cristino, 77. CEP 20921-400, São Cristóvão, Rio de Janeiro-RJ, Brazil;Optical and Infrared Astronomy Division, National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

关键词: galaxies: evolution;    galaxies: formation;    galaxies: high-redshift;    (cosmology:) large-scale structure of universe;   

DOI  :  10.1093/pasj/psx102

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We conduct a systematic search for galaxy protoclusters at z ∼ 3.8 based on the latest internal data release (S16A) of the Hyper Suprime-Cam Subaru strategic program (HSC-SSP). In the Wide layer of the HSC-SSP, we investigate the large-scale projected sky distribution of g-dropout galaxies over an area of 121 deg2, and identify 216 large-scale overdense regions (>4 σ overdensity significance) that are likely protocluster candidates. Of these, 37 are located within 8΄ (3.4 physical Mpc) of other protocluster candidates of higher overdensity, and are expected to merge into a single massive structure by z = 0. Therefore, we find 179 unique protocluster candidates in our survey. A cosmological simulation that includes projection effects predicts that more than 76% of these candidates will evolve into galaxy clusters with halo masses of at least 1014 M⊙ by z = 0. The unprecedented size of our protocluster candidate catalog allows us to perform, for the first time, an angular clustering analysis of the systematic sample of protocluster candidates. We find a correlation length of 35.0 h−1 Mpc. The relation between correlation length and number density of z ∼ 3.8 protocluster candidates is consistent with the prediction of the ΛCDM model, and the correlation length is similar to that of rich clusters in the local universe. This result suggests that our protocluster candidates are tracing similar spatial structures to those expected from the progenitors of rich clusters, and enhances the confidence that our method for identifying protoclusters at high redshifts is robust. In years to come, our protocluster search will be extended to the entire HSC-SSP Wide sky coverage of ∼ 1400 deg2 to probe cluster formation over a wide redshift range of z ∼ 2–6.

【 授权许可】

CC BY