摘要：Aims. We study the statistical properties of dusty star-forming galaxies across cosmic time, such as their number counts, luminosity functions (LF), and the dust-obscured star formation rate density (SFRD).Methods. We used the most recent de-blendedHerschelcatalogue in the COSMOS field to measure the number counts and LFs at far-infrared (FIR) and sub-millimetre (sub-mm) wavelengths. The de-blended catalogue was generated by combining the Bayesian source extraction tool XID+ and an informative prior derived from the associated deep multi-wavelength photometric data.Results. Through our de-confusion technique and based on the deep multi-wavelength photometric information, we are able to achieve more accurate measurements while at the same time probing roughly ten times below theHerschelconfusion limit. Our number counts at 250μm agree well with previousHerschelstudies. However, our counts at 350 and 500μm are below previousHerschelresults because previousHerschelstudies suffered from source confusion and blending issues. Our number counts at 450 and 870μm show excellent agreement with previous determinations derived from single-dish and interferometric observations. Our measurements of the LF at 250μm and the total IR LF agree well with previous results in the overlapping redshift and luminosity range. The increased dynamic range of our measurements allows us to better measure the faint-end of the LF and measure the dust-obscured SFRD out toz ∼ 6. We find that the fraction of obscured star formation activity is at its highest (>80%) aroundz ∼ 1. We do not find a shift of balance betweenz ∼ 3 andz ∼ 4 in the SFRD from being dominated by unobscured star formation at higher redshift to obscured star formation at lower redshift. However, we do find 3 < z < 4 to be an interesting transition period as the portion of the total SFRD that is obscured by dust is significantly lower at higher redshifts.
关键词：engalaxies: abundancesgalaxies: evolutionsubmillimeter: galaxiesgalaxies: luminosity function, mass functiongalaxies: statisticsinfrared: galaxies
