Galaxy evolution in the mid-infrared green valley: a case of the A2199
  supercluster
  We study the mid-infrared (MIR) properties of the galaxies in the A2199
supercluster at z = 0.03 to understand the star formation activity of galaxy
groups and clusters in the supercluster environment. Using the Wide-field
Infrared Survey Explorer data, we find no dependence of mass-normalized
integrated SFRs of galaxy groups/clusters on their virial masses. We classify
the supercluster galaxies into three classes in the MIR color-luminosity
diagram: MIR blue cloud (massive, quiescent and mostly early-type), MIR
star-forming sequence (mostly late-type), and MIR green valley galaxies. These
MIR green valley galaxies are distinguishable from the optical green valley
galaxies, in the sense that they belong to the optical red sequence. We find
that the fraction of each MIR class does not depend on virial mass of each
group/cluster. We compare the cumulative distributions of surface galaxy number
density and cluster/group-centric distance for the three MIR classes. MIR green
valley galaxies show the distribution between MIR blue cloud and MIR SF
sequence galaxies. However, if we fix galaxy morphology, early- and late-type
MIR green valley galaxies show different distributions. Our results suggest a
possible evolutionary scenario of these galaxies: 1) Late-type MIR SF sequence
galaxies -> 2) Late-type MIR green valley galaxies -> 3) Early-type MIR green
valley galaxies -> 4) Early-type MIR blue cloud galaxies. In this sequence,
star formation of galaxies is quenched before the galaxies enter the MIR green
valley, and then morphological transformation occurs in the MIR green valley.
