Description
The unprecedented sensitivity of wide-area, low-frequency radio surveys like the LOFAR Two-Metre Sky Survey (LoTSS) has uncovered a vast population of radio-loud AGN (RLAGN) previously missed by high-flux-density surveys such as the Third Cambridge Catalogue of Radio Sources (3CRR). As a key SKA precursor, LOFAR plays a crucial role in identifying these populations and advancing our understanding of the physical mechanisms driving RLAGN evolution.
Using 6-arcsec LoTSS DR2 (144 MHz) and 2.5-arcsec Very Large Array Sky Survey (VLASS, 3 GHz) data, we construct a flux-complete (>10 mJy), extended (>60-arcsec) sample of 2828 spectroscopically confirmed RLAGN (z<0.57) to investigate the relationship between emission-line and radio properties. We classify these sources into high- and low-excitation radio galaxies (HERG and LERG) and further categorise them into Fanaroff & Riley type I and II (FRI/FRII), wide- and narrow-angle tail (WAT/NAT), head-tail (HT), and relaxed-double (RD) morphologies. Additionally, we identify a subclass of remnant and restarted RLAGN within these morphological classes.
By analysing mid-infrared properties, host galaxy mass, and core prominence, we reveal the complex interplay between morphology, environment, and accretion processes. Our findings emphasise the need for a multi-dimensional approach to constraining RLAGN accretion modes—an effort that will be significantly enhanced by SKA’s unprecedented sensitivity and frequency coverage. This study highlights how SKA precursors like LOFAR are paving the way for next-generation radio surveys, setting the stage for transformative advances in AGN physics with the SKA Observatory (SKAO).
