ALMA Lensing Cluster Survey: Deep 1.2 mm Number Counts and Infrared Luminosity Functions at z ≃ 1–8

Ouchi, Masami; Ivison, R. J.; Koekemoer, Anton M.; Mahler, Guillaume; Richard, Johan; Smail, Ian; Fujimoto, Seiji; Shimasaku, Kazuhiro; Kohno, Kotaro; Brammer, Gabriel; Oguri, Masamune; Kneib, Jean-Paul; Egami, Eiichi; Sun, Fengwu; Ueda, Yoshihiro; Zitrin, Adi; Coe, Dan; Umetsu, Keiichi; Bradley, Larry; Toft, Sune; Bauer, Franz E.; Postman, Marc; Magdis, Georgios E.; Hatsukade, Bunyo; Jauzac, Mathilde; Wang, Tao; Wang, Wei-Hao; Kokorev, Vasily; Knudsen, Kirsten K.; Valentino, Francesco; Muñoz Arancibia, A. M.; Espada, Daniel; Ao, Yiping; Umehata, Hideki; Lagos, Claudia del P.; Dessauges-Zavadsky, Miroslava; Caminha, Gabriel B.; Uematsu, Ryosuke; Popping, Gergö; González-López, Jorge; Rawle, Timothy; Caputi, Karina; Tsujita, Akiyoshi

United States, Denmark, Japan, Netherlands, Chile, France, United Kingdom, Israel, Switzerland, Taiwan, Australia, Germany, China, Spain, Sweden

Abstract

We present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the Atacama Large Millimeter/submillimeter Array Lensing Cluster Survey (ALCS) over a total of 133 arcmin2 area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint millimeter sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing Hubble Space Telescope and Spitzer images. The dust continuum sources belong to a blind sample (N = 141) with signal-to-noise ratio (S/N) ≳ 5.0 (a purity of >0.99) or a secondary sample (N = 39) with S/N = 4.0–5.0 screened by priors. With the blind sample, we securely derive 1.2 mm number counts down to ∼7 μJy, and find that the total integrated 1.2 mm flux is Jy deg‑2, resolving ≃80% of the cosmic infrared background light. The resolved fraction varies by a factor of 0.6–1.1 due to the completeness correction depending on the spatial size of the millimeter emission. We also derive infrared (IR) luminosity functions (LFs) at z = 0.6–7.5 with the method, finding the redshift evolution of IR LFs characterized by positive luminosity and negative density evolution. The total (= UV + IR) cosmic star formation rate density (SFRD) at z > 4 is estimated to be % of the Madau and Dickinson measurements mostly based on rest-frame UV surveys. Although our general understanding of the cosmic SFRD is unlikely to change beyond a factor of 2, these results add to the weight of evidence for an additional (≈60%) SFRD component contributed by the faint millimeter population, including NIR-dark objects.

2024 The Astrophysical Journal Supplement Series
Herschel eHST 53