Groups and protocluster candidates in the CLAUDS and HSC-SSP joint deep surveys

TL;DR

This study constructs extensive galaxy group and protocluster candidate catalogs across a wide redshift range using advanced halo-based group finder techniques on combined deep survey data, aiding galaxy evolution research.

Contribution

It introduces a large-scale catalog of galaxy groups and protocluster candidates from joint deep surveys, utilizing a novel halo-based group finder capable of handling spectroscopic and photometric redshifts.

Findings

Identified over 2.2 million galaxy groups from the combined survey data.

Compiled a list of 761, 343, and 43 protocluster candidates at different redshift ranges.

Provided valuable environmental data for studying galaxy evolution over cosmic time.

Abstract

Using the extended halo-based group finder developed by Yang et al. (2021), which is able to deal with galaxies via spectroscopic and photometric redshifts simultaneously, we construct galaxy group and candidate protocluster catalogs in a wide redshift range ($0 < z < 6$) from the joint CFHT Large Area $U$-band Deep Survey (CLAUDS) and Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) deep data set. Based on a selection of 5,607,052 galaxies with $i$-band magnitude $m_{i} < 26$ and a sky coverage of $34.41\ {\rm deg}^2$, we identify a total of 2,232,134 groups, within which 402,947 groups have at least three member galaxies. We have visually checked and discussed the general properties of those richest groups at redshift $z>2.0$. By checking the galaxy number distributions within a $5-7\ h^{-1}\mathrm{Mpc}$ projected separation and a redshift difference $\Delta z \le 0.1$ around those richest groups at redshift $z>2$, we identified a list of 761, 343 and 43 protocluster candidates in the redshift bins $2\leq z<3$, $3\leq z<4$ and $z \geq 4$, respectively. In general, these catalogs of galaxy groups and protocluster candidates will provide useful environmental information in probing galaxy evolution along the cosmic time.