AGN-sCAN is a pilot radio survey carried out with the Very Long Baseline Array (VLBA) at 1.4 GHz, targeting a representative sample of 500 massive star-forming galaxies in the COSMOS field at z>0.5. 

Given a small beam size (0.027′′ ×0.007′′ , i.e. 200×50 pc at z~1) and a high sensitivity (1σ~5µJy/beam), this VLBA survey is primarily designed to identify radio-faint active galactic nuclei (AGN) without "radio excess", by leveraging the radio brightness temperature (TB) as a complementary AGN diagnostic. 

(Left): The host galaxies of our AGN-sCAN targets in the infrared luminosity (LIR) vs stellar mass (M*) plane. Our targets lie around the M*-dependent infrared-radio correlation established for star-forming galaxies (Delvecchio+2021), hence without prior evidence of radio-excess emission attributed to AGN activity. (Right): Relative fraction of radio AGN vs radio star-forming galaxies (SFGs), based on the radio-excess criterion, as a function of 1.4 GHz flux. Our VLBA survey stands between existing deep radio-continuum surveys (with VLA, MeerKAT) at low (arcsec) resolution, and future ultra-deep (sub-µJy) SKA radio surveys.  It is important to note that a small (~10%) AGN fraction is expected at our aimed sensitivity, based on current extrapolations.