A3COSMOS: The infrared luminosity function and dust-obscured star formation rate density at 0.5 < z < 6

Abstract

Aims. We leverage the largest available Atacama Large Millimeter/submillimeter Array (ALMA) survey from the archive (A3COSMOS) to study infrared luminosity function and dust-obscured star formation rate density of (sub)millimeter galaxies from z = 0.5 − 6. Methods. The A3COSMOS survey utilizes all publicly available ALMA data in the COSMOS field and therefore has inhomogeneous coverage in terms of observing wavelength and depth. In order to derive the luminosity functions and star formation rate densities, we applied a newly developed method that corrects the statistics of an inhomogeneously sampled survey of individual pointings to those representing an unbiased blind survey. Results. We find our sample to mostly consist of massive (M⋆ ∼ 1010 − 1012 M⊙) IR-bright (L* ∼ 1011 − 1013.5 L⊙) highly star-forming (SFR ∼100 − 1000 M⊙ yr−1) galaxies. We find an evolutionary trend in the typical density (Φ*) and luminosity (L*) of the galaxy population that respectively decreases and increases with redshift. Our infrared luminosity function (LF) is in agreement with previous literature results, and we were able to extend the constraints on the knee and bright end of the LF to high redshift (z > 3) by using the Herschel data. Finally, we obtained the star formation rate density up to z ∼ 6 by integrating the IR LF, finding a broad peak from z ∼ 1 to z ∼ 3 and a decline toward higher redshifts, in agreement with recent IR/millimeter-based studies, within the uncertainties. These results imply the presence of larger quantities of dust than what is expected based on optical/UV studies.