The exceptional TeV flaring activity of the blazar 1ES 1959+650 in 2015 and 2016 as observed with VERITAS

TL;DR

This paper reports on the unprecedented TeV flaring activity of blazar 1ES 1959+650 in 2015-2016, observed with VERITAS, showing multiple high-flux flares across multiple wavelengths, including the TeV band, optical, X-ray, and GeV gamma-ray.

Contribution

It provides a detailed analysis of the brightest TeV flares of 1ES 1959+650 since 2002, with multi-wavelength observations during an extended activity period.

Findings

Detected multiple high-flux TeV flares surpassing Crab nebula flux.

Observed correlated increases in optical, X-ray, and GeV gamma-ray flux.

Presented 32 hours of VERITAS data during the flaring period.

Abstract

The high-synchrotron-peaked blazar 1ES 1959+650 was among the first extragalactic sources detected in the very high energy gamma ray band (VHE, E > 100 GeV). In October 2015, the source entered an extended period of activity that continued through July 2016, during which several strong VHE flares were observed. This flaring activity in the TeV band was accompanied by a strong increase in the optical, X-ray, and GeV gamma-ray flux of the source, surpassing its brightest recorded flux states. The VERITAS telescope array performed observations of 1ES 1959+650 between October 2015 and June 2016, and detected the source multiple times at a flux higher than the Crab nebula flux in the TeV band, representing the brightest flares of this object since 2002. We here present results from the analysis of 32 hours of VERITAS observations obtained during this period and as well as a contemporaneous multi-wavelength observations in the optical, X-ray, and GeV gamma-ray bands.