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 in highly relativistic 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 present recent results ?from the VERITAS AGN observation program, highlighting long-term and ?short-term variabilities of blazars with multiwavelength and ?multimessenger observations. We also show the progress of the ?prototype Schwarzschild-Couder telescope for the Cherenkov Telescope ?Array, as well as novel gamma-ray data analysis techniques using ?machine learning.

BIO
Qi Feng's research in observational high-energy astrophysics ?focuses on three aspects: 1) variability of gamma-ray sources, ?primarily active galactic nuclei, 2) high-energy astrophysics ?instrumentation, and 3) application of machine learning algorithms in ?gamma-ray data analysis. He currently leads the blazars science ?working group and data quality monitoring group in the VERITAS ?Collaboration, and plays a significant role in the commissioning of ?the prototype Schwarzschild-Couder telescope as part of the CTA-US Collaboration.

Host: Prof. Wei Cui