Deep silence: Radio properties of little red dots

Abstract

To investigate the radio properties of the recently found high-redshift population, we collected a sample of $919$ little red dots (LRDs) from the literature. By cross-matching their co-ordinates with the radio catalogues based on the first- and second-epoch observations of the Very Large Array Sky Survey (VLASS) and the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey, we found no radio counterparts coinciding with any of the LRDs. To uncover possible sub-milli-Jansky-level weak radio emission, we performed mean and median image stacking analyses of empty-field `quick look’ VLASS and FIRST image cutouts centred on the LRD positions. We found no radio emission above $3 noise levels ($ and $ $ for the VLASS and FIRST maps, respectively) in either of the stacked images for the LRD sample, while the noise levels of the single-epoch images are comparable to those found earlier in the stacking of high-redshift radio-quiet active galactic nuclei (AGNs). The non-detection of radio emission in LRDs suggests that these sources host weaker (or no) radio AGNs.