The ALPINE-ALMA [C II] Survey: [C II] 158 μm Emission Line Luminosity Functions at z ∼ 4-6

December 2020 • 2020ApJ...905..147Y

Authors • Yan, Lin • Sajina, A. • Loiacono, F. • Lagache, G. • Béthermin, M. • Faisst, A. • Ginolfi, M. • Fèvre, O. Le • Gruppioni, C. • Capak, P. L. • Cassata, P. • Schaerer, D. • Silverman, J. D. • Bardelli, S. • Dessauges-Zavadsky, M. • Cimatti, A. • Hathi, N. P. • Lemaux, B. C. • Ibar, E. • Jones, G. C. • Koekemoer, Anton M. • Oesch, P. A. • Talia, M. • Pozzi, F. • Riechers, D. A. • Tasca, L. A. M. • Toft, Sune • Vallini, L. • Vergani, D. • Zamorani, G. • Zucca, E.

Abstract • We present the [C II] 158 μm line luminosity functions (LFs) at z ∼ 4-6 using the ALMA observations of 118 sources, which are selected to have UV luminosity M1500Å < -20.2 and optical spectroscopic redshifts in COSMOS and ECDF-S. Of the 118 targets, 75 have significant [C II] detections and 43 are upper limits. This is by far the largest sample of [C II] detections, which allows us to set constraints on the volume density of [C II] emitters at z ∼ 4-6. But because this is a UV-selected sample, we are missing [C II]-bright but UV-faint sources, making our constraints strict lower limits. Our derived LFs are statistically consistent with the z ∼ 0 [C II] LF at 108.25-109.75L. We compare our results with the upper limits of the [C II] LF derived from serendipitous sources in the ALPINE maps. We also infer the [C II] LFs based on published far-IR and CO LFs at z ∼ 4-6. Combining our robust lower limits with these additional estimates, we set further constraints on the true number density of [C II] emitters at z ∼ 4-6. These additional LF estimates are largely above our LF at L[CII] > 109L, suggesting that UV-faint but [C II]-bright sources likely make significant contributions to the [C II] emitter volume density. When we include all the LF estimates, we find that available model predictions underestimate the number densities of [C II] emitters at z ∼ 4-6. Finally, we set a constraint on the molecular gas mass density at z ∼ 4-6, with ρmol ∼ (2-7) × 107M Mpc-3. This is broadly consistent with previous studies.


IPAC Authors


Andreas Faisst

Assistant Scientist