Oral Presentation

A blind CO line-emitter search using ALMA data toward gravitational lensing clusters

Author(s): Yuki Yamaguchi (Institute of Astronomy, University of Tokyo) Kotaro Kohno (Institute of Astronomy, University of Tokyo) Yoichi Tamura (Institute of Astronomy, University of Tokyo)

Presenter: Yuki Yamaguchi (Institute of Astronomy, University of Tokyo)

We present results of a blind CO line-emitter search using ALMA Band 6 data with one frequency tuning toward 4 gravitational lensing clusters (RXJ1347.5-1145, Abell S0592, MACS J0416.1-2403, and Abell 2744). We construct 3-dimensional signal-to-noise (S/N) cubes with 60 MHz and 100 MHz binning (corresponding to ~ 66.7 km/s and ~ 111 km/s at 270 GHz, respectively) and search for CO line-emitters using the CLUMPFIND algorithm. We do not detect any new line-emitters with peak S/N > 5, although we find one line-emitter candidate with peak S/N ~ 4.5. These results provide upper limits to the CO(3-2), CO(4-3), and CO(5-4) luminosity function at z = 0.3, 0.7, and 1.2, respectively. Thanks to magnification effect of gravitational lensing clusters, we constrain CO luminosity functions down to < 10^{-3}-10^{-2} /Mpc^3 at L'co ~ 10^8-10^10 K km/s pc^2. These constraints are consistent with predictions of semi-analytic models and the latest spectroscopic scan observations of ASPECS in HUDF at same luminosity ranges. However, we can put upper limit at ~ 0.5 dex lower luminosity range than previous observations. Therefore, this study demonstrates that not only spectroscopic scan observations but also wide observations with one frequency tuning toward gravitational lensing clusters are useful to constrain CO luminosity functions.