Panoramic Views of Cluster-Scale Assemblies Explored by Subaru Wide-Field Imaging
Shimasaku, Kazuhiro; Ohashi, Takaya; Kodama, Tadayuki; Tanaka, Ichi; Matsuhara, Hideo; Umetsu, Keiichi; Yamada, Toru; Nakata, Fumiaki; Okamura, Sadanori; Tamura, Naoyuki; Arimoto, Nobuo; Ohta, Kouji; Suto, Yasushi; Tanaka, Masayuki; Kitayama, Tetsu; Tamura, Takayuki; Iye, Masanori; Kashikawa, Nobunari; Okamoto, Takashi; Futamase, Toshifumi; Kawasaki, Wataru; Nagashima, Masahiro; Yahagi, Hideki; Karasawa, Yoshikazu
Japan, Taiwan, United Kingdom
Abstract
We have started PISCES project; a panoramic imaging and spectroscopic survey of distant clusters on Subaru. It exploits the unique wide-field imaging capability of Suprime-Cam, which provides a 34' × 27' field of view corresponding to a physical area of 16 × 13 Mpc2 at z ∼ 1. We plan to target 15 clusters at 0.4 ≲ z ≲ 1.3. We report on our first results concerning the inner structures and large-scale structures of two distant clusters at z = 0.55 and 0.83 together with the earlier results on a z = 0.41 cluster. The photometric redshift technique has been applied to multi-color data in order to remove most of the foreground/background galaxies so as to isolate the cluster member candidates. We have found large-scale filamentary structures around the clusters, extending out to > 5 Mpc from the cores, as well as complex inner structures. The galaxy distributions in the inner regions of the clusters look similar to the X-ray intensity maps, suggesting that most of the optical structures trace physically bound systems. We also compared the structures of the three clusters with those of model clusters in a numerical simulation (N-body + semi-analytic model) by parameterising the shapes of the iso-density contours of galaxies, and found a broad agreement. Our results that cluster-scale assembly takes place along filaments during hierarchical clustering need to be confirmed spectroscopically in the near future.