Target of opportunity observations of flaring blazars with VERITAS

TL;DR

This paper discusses VERITAS's target of opportunity observations of flaring blazars triggered by optical and GeV alerts, highlighting the multiwavelength approach to studying gamma-ray variability in these active galactic nuclei.

Contribution

It presents the methodology and results of VERITAS's follow-up observations of flaring blazars based on external alerts over two seasons, emphasizing multiwavelength coordination.

Findings

Detection of gamma-ray flares in blazars during follow-up observations

Correlation between optical/GeV alerts and VHE gamma-ray activity

Enhanced understanding of blazar variability mechanisms

Abstract

VERITAS is an array of four imaging atmospheric Cherenkov telescopes that observes gamma-ray sources in the very high energy range (VHE, E>100 GeV). A large fraction of the known gamma-ray sources are of extragalactic origin and belong to the blazar class: active galactic nuclei with relativistic jets pointing along the line of sight. Gamma-ray emission from blazars is typically variable. Part of the VERITAS observation program is devoted to follow-up triggers on flaring blazars, initiated by observations at other wavelengths. We will present those target of opportunity observations based on optical and GeV (Fermi-LAT) alerts performed with VERITAS during the past 2 seasons, and discuss the results in a multiwavelength context.