2015MNRAS.451.1141M

We present a result of a blind search for [Cii] 158µm emitters at z ∼ 4.5 using Atacama Large Millimeter Array (ALMA) Cycle 0 archival data. We collected extragalactic data covering at 330-360 GHz (band 7) from 8 Cycle 0 projects from which initial results have been already published. The total number of fields is 243 and the total on-source exposure time is 19.2 h. We searched for line emitters in continuum-subtracted data cubes with spectral resolutions of ∼ 50, 100, 300 and 500 km/s. We could not detect any new line emitters above a 6σ significance level. This result provides upper limits to the [Cii] luminosity function at z ∼ 4.5 over L_[C II] ∼10^8-10^10  L_☉ or star formation rate, SFR ∼ 10^–1000 M_^☉/yr. These limits are at least two orders of magnitude larger than the [Cii] luminosity functions expected from the z ∼ 4 UV luminosity function or from numerical simulation. However, this study demonstrates that we would be able to better constrain the [Cii] luminosity function and to investigate possible contributions from dusty galaxies to the cosmic star formation rate density by collecting Cycle 1+2 archival data as the ALMA Patchy Deep Survey.