Tracing Radio AGN-Driven Quenching in Post-Starburst Galaxies at Cosmic Noon

We present a radio continuum study of photometrically selected cosmic noon (0.5<z<3) post-starburst galaxies (PSBs) in the UKIDSS Deep Survey (UDS) field to assess if radio-mode Active Galactic Nuclei (AGN) are linked to the quenching of star formation at cosmic noon. Our cross-matching using the deep Very Large Array (VLA) imaging at 1.4 GHz results in a mean radio detection fraction (f det) of only 0.8 % for PSBs above a radio luminosity threshold of L 1.4 GHz at least 10 24 W Hz-1, increasing to 5 plus or minus2% for massive PSBs with stellar masses M*>10 11 M. Massive PSBs have a comparable detection fraction to that of massive quiescent galaxies (f det=8 plus or minus1%), and both classes have lower fractions than that of massive star-forming galaxies (f det=13 plus or minus1%) in the same field. The radio luminosities of detected PSBs, L 1.4 about 10 22.8-10 24.9 W/Hz, exceed those from star formation by a median factor of 37 indicative of a possible AGN origin. Their compact morphologies (15 kpc at z med=1.5) suggest low-luminosity AGN with less powerful jets. Stacking the undetected PSBs reveals a weak radio detection (3.9σ) in the highest mass bin (M*>10 11 M). In contrast, 1.4 GHz detected quiescent galaxies have radio luminosities reaching radio-loud levels, and a higher prevalence of extended morphologies indicative of large-scale jetted AGN. The AGN contribution is also detected in stacked measurements of quiescent galaxies. Overall, our results support a short radio AGN duty cycle for PSBs, characterized by weak radio jets, suggesting radio-driven maintenance mode feedback may become important at older ages.