In this report we would like to discuss recent developments in ground-based gamma-ray astrophysics. Since the 1990s, very high energy gamma rays have been studied with the Imaging Atmospheric Cherenkov Telescopes (IACT), which measure the Cherenkov light component of air showers. These have high sensitivity in a field of view of several degrees and can provide angular resolution on the order...
The Cherenkov Telescope Array will bring an entirely new view on high-energy transients. This opportunity will be enhanced by the coming on line of various large field-of-view ground-based and orbiting facilities that will paint a multi-wavelength picture of the variable sky. I will discuss some of the exploration areas and projects development, including the VST Polarimetric camera (VSTPol).
Extragalactic TeV astronomy with Cherenkov telescopes is synergistic with multi-frequency and multi-messenger observations, conducted through observational campaigns or triggers (target of opportunities).
We will outline these two main directions by presenting recent results from multifrequency observations of blazars, such as the quasi-periodic PG1553+113, and by discussing the prospects...
The acceleration of charged particles to very high energies in powerful astrophysical sources such as pulsar winds, active galactic nuclei, gamma-ray bursts etc., represents a central question in modern high-energy astrophysics, astroparticle physics and nowadays, multi-messenger astronomy. Accelerated particles can interact with and radiate in ambient fields to produce secondary photon or...
The modern radio sky surveys have shown that compact radio sources, so named FR0 radio galaxies, are the majority among radio loud active galactic nuclei of the local Universe. The numerous FR0 population have to make a significant contribution to cosmic background emissions. These sources have mildly relativistic jets at parsec scales despite lack of prominent extended kpc radio structures....
