TANAMI III. First-epoch S band images

We performed VLBI observations of TeV-detected AGN and high likelihood neutrino associations as of December of 2021 with the Long Baseline Array (LBA) and other southern hemisphere radio telescopes at 2.3GHz. In this paper we present first light TANAMI S-band images, focusing on the TeV-detected sub-sample of the full TANAMI sample. Apart from these very high energy-detected sources, we also show images of the two flux density calibrators and two additional sources included in the observations.

We study the redshift, 0.1-100GeV photon flux and S-band core brightness temperature distributions of the TeV-detected objects, and find that flat spectrum radio quasars and low synchrotron peaked sources on average show higher brightness temperatures than high-synchrotron-peaked BL Lacs. Sources with bright GeV gamma-ray emission also show higher brightness temperature values than gamma-low sources. Long-term monitoring programs are crucial to study the multi-wavelength properties of active galactic nuclei.

With the successful detection of even the faintest sources with flux densities below 50mJy, future work will entail kinematic analysis and spectral studies both at 2.3 and 8.4GHz to investigate the connection between the radio and gamma-ray activity of these objects.