J-HERTz: a radio counterpart catalogue for J-PLUS

We present J-HERTZ (J-Plus Heritage Exploration of Radio Targets at Z <
5) a new value-added catalogue associated with the J-PLUS DR3 release,
including sources with counterparts at low radio frequencies detected
by the LOFAR LoTSS DR2 survey. The catalogue comprises about 470k
objects within a common area of approximately 2100 deg².

J-HERTZ includes a machine-learning classification of the galaxies,
QSOs and stars in the survey, based on Bayesian neural networks (BANNJO
S, del Pino et al. 2024, submitted). Additionally, BANNJOS provides new
photometric redshifts for sources without previous spectroscopic
observations. The complete catalogue includes 370k galaxies,
30k QSOs and 20k stars detected with high confidence (r < 20
mag). In this work we describe the main properties of these three
populations, including the galaxy stellar masses derived from CIGALE
fitting to the J-PLUS photospectra (Arizo et al. in prep.), the AGN
luminosity and radio-loudness distribution, and the presence of stars
with activity at radio frequencies. J-HERTZ is publicly available
through the J-PLUS DR3 online repository.