%0 Journal Article
%T Radio Galaxies¡ªThe TeV Challenge
%A Bindu Rani
%J Galaxies | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/galaxies7010023
%X Over the past decade, our knowledge of the ¦Ã -ray sky has been revolutionized by ground- and space-based observatories by detecting photons up to several hundreds of tera-electron volt (TeV) energies. A major population of the ¦Ã -ray bright objects are active galactic nuclei (AGN) with their relativistic jets pointed along our line-of-sight. Gamma-ray emission is also detected from nearby misaligned AGN such as radio galaxies. While the TeV-detected radio galaxies ( T e V R a d ) only form a small fraction of the ¦Ã -ray detected AGN, their multi-wavelength study offers a unique opportunity to probe and pinpoint the high-energy emission processes and sites. Even in the absence of substantial Doppler beaming T e V R a d are extremely bright objects in the TeV sky (luminosities detected up to 10 45 erg s £¿ 1 ), and exhibit flux variations on timescales shorter than the event-horizon scales (flux doubling timescale less than 5 min). Thanks to the recent advancement in the imaging capabilities of high-resolution radio interferometry (millimeter very long baseline interferometry, mm-VLBI), one can probe the scales down to less than 10 gravitational radii in T e V R a d , making it possible not only to test jet launching models but also to pinpoint the high-energy emission sites and to unravel the emission mechanisms. This review provides an overview of the high-energy observations of T e V R a d with a focus on the emitting sites and radiation processes. Some recent approaches in simulations are also sketched. Observations by the near-future facilities like Cherenkov Telescope Array, short millimeter-VLBI, and high-energy polarimetry instruments will be crucial for discriminating the competing high-energy emission models. View Full-Tex
%U https://www.mdpi.com/2075-4434/7/1/23