2017/08/21 by Q. Feng, S. G. Jorstad, Feng, Q. +25 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #Gyrotron and Vacuum Electronics Research #High Energy Astrophysical Phenomena (astro-ph.HE) #Radio Astronomy Observations and Technology
paper · pdf · doi:10.48550/arxiv.1708.06386
openalex publication_date 2017/08/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Observations of fast TeV γ-ray flares from blazars reveal the extreme compactness of emitting regions in blazar jets. Combined with very-long-baseline radio interferometry measurements, they probe the structure and emission mechanism of the jet. We report on a fast TeV γ-ray flare from BL Lacertae observed by VERITAS, with a rise time of about 2.3 hours and a decay time of about 36 minutes. The peak flux at >200 GeV measured with the 4-minute binned light curve is (4.2 ± 0.6) × 10-6 photons m-2 s-1, or ∼180% the Crab Nebula flux. Variability in GeV γ-ray, X-ray, and optical flux, as well as in optical and radio polarization was observed around the time of the TeV γ-ray flare. A possible superluminal knot was identified in the VLBA observations at 43 GHz. The flare constrains the size of the emitting region, and is consistent with several theoretical models with stationary shocks.