ACCESS II: A Complete Census of Star Formation in the Shapley
  Supercluster - UV and IR Luminosity Functions
  We present panoramic Spitzer/MIPS mid- and far-infrared and GALEX ultraviolet
imaging of the the most massive and dynamically active system in the local
Universe, the Shapley supercluster at z=0.048, covering the 5 clusters which
make up the supercluster core. We combine these data with existing
spectroscopic data from 814 confirmed supercluster members to produce the first
study of a local rich cluster including both ultraviolet and infrared
luminosity functions (LFs). This joint analysis allows us to produce a complete
census of star-formation (both obscured and unobscured), extending down to
SFRs~0.02-0.05Msun/yr, and quantify the level of obscuration of star formation
among cluster galaxies, providing a local benchmark for comparison to ongoing
and future studies of cluster galaxies at higher redshifts with Spitzer and
Herschel. The GALEX NUV and FUV LFs obtained have steeper faint-end slopes than
the local field population, due largely to the contribution of massive,
quiescent galaxies at M_FUV>-16. The 24um and 70um galaxy LFs for the Shapley
supercluster instead have shapes fully consistent with those obtained for the
Coma cluster and for the local field galaxy population. This apparent lack of
environmental dependence for the shape of the FIR luminosity function suggests
that the bulk of the star-forming galaxies that make up the observed cluster
infrared LF have been recently accreted from the field and have yet to have
their star formation activity significantly affected by the cluster
environment. We estimate a global SFR of 327 Msun/yr over the whole
supercluster core, of which just ~20% is visible directly in the UV continuum
and ~80% is reprocessed by dust and emitted in the infrared. The level of
obscuration (L_IR/L_FUV) in star-forming galaxies is seen to increase linearly
with L_K over two orders of magnitude in stellar mass.
