Letters of Intent received in 2016

LoI 2018-1943
Radio Galaxies: Resolving the AGN phenomenon

Date: 22 August 2018 to 23 August 2018
Category: Focus meetings (GA)
Location: Vienna, Austria
Contact: Volker Beckmann (beckmann@in2p3.fr)
Coordinating division: Division D High Energy Phenomena and Fundamental Physics
Other divisions: Division B Facilities, Technologies and Data Science
Division H Interstellar Matter and Local Universe
Division J Galaxies and Cosmology
Co-Chairs of SOC: Diana Worrall (University of Bristol)
Claudio Ricci (Universidad Catolica de Chile)
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Co-Chairs of LOC: ()
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Topics

Triggers of highly relativistic jets
Jet collimation
Radio galaxies as VHE photon emitters
Knots, hotspots and other structural features
The central engine
Radiative versus jet mode
Radio galaxy populations and statistics
Origin and evolution of radio galaxies
Interaction with the environment
Future telescopes' view on radio galaxies

 

Rationale

Radio galaxies provide us with natural laboratories for a wide range of (astro)physical processes. As they are the parent population of the whole class of beamed active galactic nuclei (AGN), understanding radio galaxies is vital for deriving a complete picture of accretion and emission throughout the Universe. Radio galaxies show us the most important aspects of AGN: the central engine with potential obscuration, the accretion process with its characteristic features, relativistic emission in the form of jets with knots and shocks, and radio lobes with occasional hot spots and visible interaction with the surrounding medium. This makes them unique sources to answer questions like:
• What triggers highly relativistic jets - and how are they launched?
• How are the jets so well collimated very close to the central engine and how are they confined over a distance of, in some cases, several 100 kpc?
• How do radio galaxies emit VHE photons into the line of sight?
• Why is there no hot spot seen in some radio lobes?
• Are all radio galaxies obscured?
• Why are some AGN in the radiative mode while others are in the jet mode?
• What are the intrinsic differences between low-excitation and high-excitation radio galaxies and how do these relate to the FR-I/II classification?
• What is the high-redshift luminosity function of radio galaxies and how does it evolve to the present day Universe?
• How do radio galaxies interact with their environment?

The IAU General Assembly in 2018 will be an excellent occasion to discuss these and other aspects of radio galaxies. Planck's data will be fully analysed and available, providing a rich data set for studies in the 30-900 GHz range. The assembly will also take place while the first data of the Cherenkov Telescope Array (CTA) are becoming available --- we expect the number of known VHE-emitting radio galaxies to increase dramatically, and spectra of already-known VHE emitters to improve significantly. eROSITA will provide its first all-sky survey in the X-ray domain, providing an improved census of radio galaxies in this energy band, important for studies of the accretion history of super-massive black holes. In addition, 2018 will be an excellent time to discuss radio galaxies in the context of large future experiments, such as E-ELT, SKA, and Athena.