We present the results of a blind millimeter line emitter search using ALMA Band 6 data with a single frequency tuning toward four gravitational lensing clusters (RXJ1347.5-1145, Abell S0592, MACS J0416.1-2403, and Abell 2744). We construct three-dimensional signal-to-noise ratio (S/N) cubes with 60 MHz and 100 MHz binning, and search for millimeter line emitters. We do not detect any line emitters with a peak S/N > 5, although we do find a line emitter candidate with a peak S/N ~ 4.5. These results provide upper limits to the CO(3-2), CO(4-3), CO(5-4), and [CII] luminosity functions at z ~ 0.3, 0.7, 1.2, and 6, respectively. Because of the magnification effect of gravitational lensing clusters, the new data provide the first constraints on the CO and [CII] luminosity functions at unprecedentedly low luminosity levels, i.e., down to <10−3−10−1Mpc−3 dex−1 at LCO′108−1010 K km s−1 pc2 and <10−3−10−2 Mpc−3 dex−1 at L[CII]108−1010L⊙, respectively. Although the constraints to date are not stringent yet, we find that the evolution of the CO and [CII] luminosity functions are broadly consistent with the predictions of semi-analytical models. This study demonstrates that the wide observations with a single frequency tuning toward gravitational lensing clusters are promising for constraining the CO and [CII] luminosity functions.
@article{arxiv.1707.05547,
title = {Blind millimeter line emitter search using ALMA data toward gravitational lensing clusters},
author = {Yuki Yamaguchi and Kotaro Kohno and Yoichi Tamura and Masamune Oguri and Hajime Ezawa and Natsuki H. Hayatsu and Tetsu Kitayama and Yuichi Matsuda and Hiroshi Matsuo and Tai Oshima and Naomi Ota and Takuma Izumi and Hideki Umehata},
journal= {arXiv preprint arXiv:1707.05547},
year = {2017}
}