2025A&A...696A.193B

To understand early star formation, it is essential to determine the dust mass budget of high-redshift galaxies. Sub-millimeter rest-frame emission, dominated by cold dust, is an unbiased tracer of dust mass. The New IRAM KID Arrays 2 (NIKA2) conducted a deep blank field survey at 1.2 and 2.0 mm in the GOODS-N field as part of the NIKA2 Cosmological Legacy Survey (N2CLS), detecting 65 sources with S/N ≥ 4.2. Thanks to a dedicated interferometric program with NOEMA and other high-angular resolution data, we identified the multi-wavelength counterparts of these sources and resolved them into 71 individual galaxies. We built detailed spectral energy distributions (SEDs) and assigned a redshift to 68 of them over the range 0.6 < z < 7.2. We fit these SEDs using modified blackbody and Draine & Li (2007, ApJ, 657, 810) models and the panchromatic approaches MAGPHYS, CIGALE, and SED3FIT, thus deriving their dust mass (M_dust), infrared luminosity (L_IR), and stellar mass (M_⋆). Eight galaxies require an active galactic nucleus torus component, and another six require an unextinguished young stellar population. A significant fraction of our galaxies are classified as starbursts based on their position on the M_⋆ versus star formation rate plane or their depletion timescales. We computed the dust mass function in three redshift bins (1.6 < z ≤ 2.4, 2.4 < z ≤ 4.2 and 4.2 < z ≤ 7.2) and determined the Schechter function that best describes it. The dust cosmic density, ρ_dust, increases by at least an order of magnitude from z ∼ 7 to z ∼ 1.5, as predicted by theoretical works. At lower redshifts, the evolution flattens. Nonetheless, significant differences exist between results obtained with different selections and methods. The superb GOODS-N data set enabled a systematic investigation into the dust properties of distant galaxies. N2CLS holds promise for combining these deep field findings with the wide COSMOS field into a self-consistent analysis of dust in galaxies both near and far.