The Local [CII] 158 um Emission Line Luminosity Function
  We present, for the first time, the local [CII] 158 um emission line
luminosity function measured using a sample of more than 500 galaxies from the
Revised Bright Galaxy Sample (RBGS). [CII] luminosities are measured from the
Herschel PACS observations of the Luminous Infrared Galaxies in the Great
Observatories All-sky LIRG Survey (GOALS) and estimated for the rest of the
sample based on the far-IR luminosity and color. The sample covers 91.3% of the
sky and is complete at S_60 um > 5.24 Jy. We calculated the completeness as a
function of [CII] line luminosity and distance, based on the far-IR color and
flux densities. The [CII] luminosity function is constrained in the range
~10^(7-9) (Lo) from both the 1/V_max and a maximum likelihood methods. The
shape of our derived [CII] emission line luminosity function agrees well with
the IR luminosity function. For the CO(1-0) and [CII] luminosity functions to
agree, we propose a varying ratio of [CII]/CO(1-0) as a function of CO
luminosity, with larger ratios for fainter CO luminosities. Limited [CII] high
redshift observations as well as estimates based on the IR and UV luminosity
functions are suggestive of an evolution in the [CII] luminosity function
similar to the evolution trend of the cosmic star formation rate density. Deep
surveys using ALMA with full capability will be able to confirm this
prediction.
