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