Extragalactic Cosmic Accelerators Through the Eyes of Ground-Based Gamma-Ray Telescopes

Some of the fastest and most energetic flares from active galactic nuclei (AGN) have been observed by ground-based gamma-ray telescope arrays, like the Very Energetic Radiation Imaging Telescope Array System (VERITAS). These flares provide strong constraints on the size and Doppler factor of the emitting regions that move at relativistic speed in AGN jets. However, it is not an easy task to pinpoint the location of gamma-ray emitting region because of the limited angular resolution of the instruments. Multiwavelength observations contemporaneous to the gamma-ray flares make this task possible. We will present recent highlights from the VERITAS AGN observation program, including long-term and short-term variability of blazars, constraints on the EBL density, and the detections of a blazar potentially associated with astrophysical neutrinos, a new radio galaxy, and distant flat-spectrum radio qausars. We will also show the progress of the prototype Schwarzschild-Couder telescope for the Cherenkov Telescope Array, as well as novel analysis techniques using deep learning.

Qi Feng (Columbia University)
first floor meeting room
Fri, 2018-12-21 12:00 to 13:00