Confirmation of a Substantial Discrepancy between Radio and UV--IR Measures of the Star Formation Rate Density at 0.2 < z < 1.3

A. M Matthews, D. D. Kelson, A. B. Newman, F. Camilo, J. J. Condon, W. D. Cotton, M. Dickinson, T. H. Jarrett, M. Lacy

Published 2023-10-26Version 1

We present the initial sample of redshifts for 3,839 galaxies in the MeerKAT DEEP2 field -- the deepest $\sim$1.4\,GHz radio field yet observed. Using a spectrophotometric technique combining coarse optical spectra with broadband photometry, we obtain redshifts with $\sigma_z \leq 0.01(1+z)$. The resulting radio luminosity functions between $0.2<z<1.3$ from our sample of 3,839 individual galaxies are in remarkable agreement with those inferred from modeling radio source counts, confirming an excess in radio-based SFRD$(z$) measurements at late times compared to those from the UV--IR. Several sources of systematic error are discussed -- with most having the potential of exacerbating the discrepancy -- with the conclusion that significant work remains to have confidence in a full accounting of the star formation budget of the universe.