Pre-processing of galaxies in cosmic filaments around AMASCFI clusters
  in the CFHTLS
  Galaxy clusters and groups are thought to accrete material along the
preferred direction of cosmic filaments. Yet these structures have proven
difficult to detect due to their low contrast with few studies focusing on
cluster infall regions. In this work, we detected cosmic filaments around
galaxy clusters using photometric redshifts in the range 0.15<z<0.7. We
characterised galaxy populations in these structures to study the influence of
"pre-processing" by cosmic filaments and galaxy groups on star-formation
quenching. The cosmic filament detection was performed using the AMASCFI
Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) T0007 cluster sample
(Sarron et al. 2018). The filament reconstruction was done with the DISPERSE
algorithm in photometric redshift slices. We showed that this reconstruction is
reliable for a CFHTLS-like survey at 0.15<z<0.7 using a mock galaxy catalogue.
We split our galaxy catalogue in two populations (passive and star-forming)
using the LePhare SED fitting algorithm and worked with two redshift bins
(0.15<z<=0.4 and 0.4<z<0.7). We showed that the AMASCFI cluster connectivity
(i.e. the number of filaments connecting to a cluster) increases with cluster
mass M200. Filament galaxies outside R200 are found to be closer to clusters at
low redshift, whatever the galaxy type. Passive galaxies in filaments are
closer to clusters than star-forming galaxies in the low redshift bin only. The
passive fraction of galaxies decreases with increasing clustercentric distance
up to d~5 cMpc. Galaxy groups/clusters that are not located at nodes of our
reconstruction are mainly found inside cosmic filaments. These results give
clues for "pre-processing" in cosmic filaments, that could be due to smaller
galaxy groups. This trend could be further explored by applying this method to
larger photometric surveys such as HSC-SPP or Euclid.
