Very-high-energy blazars: updates from VERITAS observations and multi-wavelength campaigns

TL;DR

This paper reports recent VERITAS observations of over twenty extragalactic VHE sources, highlighting key multi-wavelength campaigns and significant flares from blazars, advancing understanding of their high-energy emission mechanisms.

Contribution

It provides new observational results from VERITAS on blazar flares and long-term monitoring, emphasizing multi-wavelength campaign insights and detection of the farthest VHE emitter.

Findings

Detection of PKS 1222+216 during March 2014

Gamma-ray flare from 1ES 1727+502 in May 2013

Bright gamma-ray flare from 1ES 1011+496 in February 2014

Abstract

VERITAS is an array of four 12-m atmospheric Cherenkov telescopes, designed to observe the very-high-energy (VHE; E $\geq$100 GeV) sky. Since 2007, it has detected more than 20 extra-galactic sources, the majority of which are active-galactic-nuclei of the blazar class. In this paper we present a selection of the most recent results from the VERITAS blazar observing program, in particular in the context of broad-band multi-wavelength campaigns. Four results are highlighted: the detection of the flat-spectrum-radio-quasar PKS 1222+216 (4C +21.35) during March 2014; the $\gamma$-ray flare from the BL Lac object 1ES 1727+502, observed under bright-moonlight conditions during May 2013; the bright $\gamma$-ray flare from the BL Lac object 1ES 1011+496 during February 2014; and the long-term campaign on the BL Lac object PKS 1424+240, currently the farthest (z > 0.60), persistent VHE emitter