DOI

https://doi.org/10.48717/frr8-4s73

Project

ES111

Title

ES111

Abstract

Whether galactic radio jets are regulated by accretion rate onto supermassive black holes is still an unsolved problem. Previous radio studies were mainly performed as follow-ups in response to optical and X-ray selected transients, such as tidal disruption events and changing-look AGNs. These studies reveal a low radio detection rate (~10%) and low radio luminosities, of which the origin is controversial. Using the recently released VLASS epoch III data at 3 GHz as well as GMRT follow-up, we have identified a unique ancient galaxy with on-going radio outburst, which is however completely silent in optical and mid-IR photometric observations. With an equipartition analysis on the radio SED evolution over about three years, we find the radio-emitting region is expanding with a velocity of 0.15c and 0.06c for collimated and spherical outflow, respectively. We request timely multi-frequency EVN observations with the aim to precisely localize the radio emission, and probe the radio structure at a milliarcsecond scale, resolving jet-like/outflow components if present. The EVN observations will also provide measurement of radio spectral slope which will help to uncover the origin of radio outburst via better characterizing its SED evolution.