Affiliation: University of Edinburgh

Contribution: Oral

Title: Dust-obscured star formation in the young Universe revealed by combining JWST PRIMER with ALMA

Abstract: A significant fraction of star formation over cosmic history is obscured by dust, which absorbs UV light and re-emits at far-infrared/millimeter wavelengths. However, completing our census of cosmic star formation, combining the unobscured (UV/optical) and obscured (far-infrared/mm) star-forming galaxy populations has proved challenging due to the difficulties of combining datasets at very different wavelengths (and often different resolutions). Indeed, many dusty sources detected at (sub-)mm wavelengths have proved difficult to detect at short wavelengths, even with Hubble. However, the additional depth and near-infrared wavelength coverage delivered by JWST is now transforming this field. Aided by the excellent astrometric accuracy delivered by both JWST and ALMA, we here use the (now complete) JWST PRIMER NIRCam+MIRI imaging in the COSMOS PRIMER field to identify the galaxy counterparts to 99% of the known mm-wavelength sources in the field, as revealed by the ALMA A3COSMOS database. Never before has such a large and deep mm-wavelength sample been essentially completely and robustly identified at rest-frame optical wavelengths, and we use detailed spectral evolution fitting to determine the redshift distribution and physical properties (star-formation rates, ages, stellar masses) of the dust-enshrouded population. Moreover, the mm depth and optical ID completeness of our sample enables us to set new constraints on the contribution of dust-enshrouded galaxies to the rise of star-formation density at early times.

This contribution can be found here (pdf).