Landing page for project EK062

Blazars constitute the majority of extragalactic gamma-ray sources and significantly contribute to the radiation observed in the even higher energy regime. The upcoming Cherenkov Telescope Array (CTA) is expected to detect fainter TeV objects. Balmaverde et al. (2020) compiled a list of 14 X-ray and radio-detected sources that are good candidates for being TeV-emitting sources (Te-REXes). Out of this sample, we have previously observed two that did not show sign of an active nucleus (categorized as passive elliptical galaxies, PEGs) but the authors hypothesized that they contain a faint AGN, overshone by its host galaxy. Our results suggest that both of these optically passive-looking galaxies host faint compact radio-emitting AGN. This proposal aims to use the EVN and e-MERLIN to observe the remaining 4 faint radio sources which were not targeted by VLBI before, to identify the origin of their radio emission. We want to confirm whether a faint AGN resides in the optically passive-looking galaxies, and distinguish between jet-related and corona-related radio emission. Since TeV emission is expected from jetted sources, the VLBI observations can help constrain the expected number of TeV sources detectable by CTA.

This data is part of the archive of VLBI data maintained by JIVE on behalf of the EVN, a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa. The EVN archive itself has the DOI https://doi.org/10.17616/R3Z197