SPITZER observations of Abell 1763. III. The infrared luminosity
  function in different supercluster environments
  We determine the galaxy infrared (IR) luminosity function (LF) as a function
of the environment in a supercluster at z=0.23, using optical, near-IR, and
mid- to far-IR photometry, as well as redshifts from optical spectroscopy. We
identify 467 supercluster members in a sample of 24-micron-selected galaxies,
on the basis of their spectroscopic (153) and photometric (314) redshifts. IR
luminosities, stellar masses and star formation rates (SFRs) are determined for
supercluster members via spectral energy distribution fitting and the Kennicutt
relation. Galaxies with active galactic nuclei are excluded from the sample. We
determine the IR LF of the whole supercluster as well as the IR LFs of three
different regions in the supercluster: the cluster core, a large-scale
filament, and the cluster outskirts (excluding the filament). The IR LF shows
an environmental dependence which is not simply related to the local galaxy
density. The filament, an intermediate-density region in the A1763
supercluster, contains the highest fraction of IR-emitting galaxies at all
levels of IR luminosities. As expected, the core contains the lowest fraction
of IR-emitting galaxies and almost no Luminous IR Galaxies (LIRGs). The
relation between galaxy specific SFRs and stellar masses does not depend on the
environment, and it indicates that most supercluster LIRGs (in particular those
in the filament) are rather massive galaxies with relatively low specific SFRs.
A comparison with previous IR LF determinations from the literature confirms
that the mass-normalized total SFR in clusters increases with redshift, but
more rapidly than previously suggested for redshifts <0.4. We interpret our
findings within a possible scenario for the evolution of galaxies in and around
clusters [Abridged].
