Invited Presentation

A systematic search for protoclusters based on Subaru/HSC survey

Author(s): Jun Toshikawa

Presenter: Jun Toshikawa (University of Tokyo)

We conduct a systematic search for galaxy protoclusters at z~3.8 based on 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 121deg^2, and identify 216 large-scale overdense regions that are likely protocluster candidates. 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 35.0Mpc. The relation between correlation length and number density of z~3.8 protocluster candidates is consistent with the prediction of the CDM 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. Following this protocluster search, we are now performing follow-up observations to investigate the physical properties of protoclusters. Optical spectroscopy is carried out for four protocluster candidates by Keck/DEIMOS and Gemini/GMOS, and five protocluster candidates are observed by the submm imaging of JCMT/SCUBA2 to search dusty star-burst galaxies. We will present the systematic search for protoclusters and the initial results of these follow-up observations. In years to come, our protocluster search will be extended to the entire HSC-SSP Wide sky coverage to probe cluster formation over a wide redshift range of z~2-6.