[CII] luminosities of galaxies in G.A.S.+Cloudy

We studied the L[CII]-SFR and L[CII]-Zg relations and show that they do not strongly evolve with redshift from z=4 and to z=8. Galaxies with higher [CII] luminosities tend to have higher metallicities and higher star formation rates but the correlations are very broad, with a scatter of about 0.5 and 0.8dex for L[CII]-SFR and L[CII]-Zg, respectively. Our model reproduces the L[CII]-SFR relations observed in high-redshift star-forming galaxies, with [CII] luminosities lower than expected from local L[CII]-SFR relations.

Accordingly, the local observed L[CII]-SFR relation does not apply at high-z (z~=5), even when CMB effects are ignored. Our model naturally produces the [CII] deficit (i.e. the decrease of L[CII]/LIR with LIR), which appears to be strongly correlated with the intensity of the radiation field in our simulated galaxies. We then predict the [CII] luminosity function, and show that it has a power law form in the range of L[CII] probed by the model with a slope {alpha}=-1.

The slope is not evolving from z=4 to z=8 but the number density of [CII]-emitters decreases by a factor of 20x. We discuss our predictions in the context of current observational estimates on both the differential and cumulative luminosity functions. The outputs from the model are distributed as FITS-formatted files at the CDS.