(Proposal ID) S17B-017

(PI) Hayashi, Masao

(Proposal Title)
3D large-scale structures at z=0.4 revealed by two adjacent narrow-band filters

(Abstract)
We propose HSC imaging with our{custom-made} NB926 narrowband (NB) filter in 
the HSC-SSP DEEP2-3 field. The HSC-SSP NB921 data have  revealed an amazing 
large scale structure traced by H alpha emission line galaxies at z~0.4 over 
a >40 comoving Mpc scale which includes two galaxy clusters identified by a 
red sequence galaxy finder. We aim to map out the large scale structures in 
and around the clusters at z~0.4 in 3D without any effect of projection using 
the combination of NB921 and NB926 data. Thanks to a slight difference 
(50Angstrom) of central wavelength between  the two NB filters, the flux ratio 
of the same emission line observed through the two NB filters is dependent on 
the redshift of galaxy. This unique method can improve an accuracy of the 
estimated redshifts by about an order of magnitude compared with the redshift 
range of galaxies selected with single NB (Delta z ~0.02). Using the 3D 
distribution, we identify the accretion phase of the  galaxies associated 
with the galaxy clusters and the cosmic web based on the phase-space diagram 
showing velocity versus distance around the cluster center. We investigate 
the dependence of galaxy properties on the accretion phase and then discuss 
the physical processes responsible for the evolution of cluster galaxies.