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

We present the [C II] 158 μ m line luminosity functions (LFs) at z ∼ 4–6 using the ALMA observations of 118 sources, which are selected to have UV luminosity M 1500Å 10 9 L ⊙ , 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 ρ mol ∼ (2–7) × 10 7 M ⊙ Mpc −3 . This is broadly consistent with previous studies.