2023/03/03 by Seiji Fujimoto, Kotaro Kohno, Fujimoto, Seiji +82 · 5 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Astronomy and Astrophysical Research #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2303.01658
We present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the ALMA Lensing Cluster Survey (ALCS) over a total of 133 arcmin2 area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint mm sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing \it Hubble Space Telescope and \it Spitzer images. The dust continuum sources belong to a blind sample (N=141) with S/N \gtrsim 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 1.2mm flux is 20.7+8.5-6.5 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 mm emission. We also derive infrared (IR) luminosity functions (LFs) at z=0.6-7.5 with the 1/V\rm max 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 161+25-21 % of the established measurements, which were almost exclusively based on optical-NIR 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-mm population, including NIR dark objects.