Impact of Galaxy Mergers on the Colours of Cluster Galaxies
  We examine the ultraviolet and optical colours of 906 cluster galaxies from
the KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC). Galaxies have been
divided into two categories, morphologically-disturbed and undisturbed
galaxies, based on the visual signatures related to recent mergers. We find
that galaxies with signatures of recent mergers show significantly bluer
colours than undisturbed galaxies. Disturbed galaxies populate more on the
cluster outskirts, suggesting recent accretion into the cluster environment,
which implies that disturbed galaxies can be less influenced by the
environmental quenching process and remain blue. However, we still detect bluer
colours of disturbed galaxies in all locations (cluster core and outskirts) for
the fixed morphology, which is difficult to understand just considering the
difference in time since infall into a cluster. Moreover, blue disturbed
galaxies show features seemingly related to recent star formation. Therefore,
we suspect that mergers make disturbed galaxies keep their blue colour longer
than undisturbed galaxies under the effect of the environmental quenching
through either merger-induced star formation or central gas concentration which
is less vulnerable for gas stripping.
