Discovery of Very High Energy gamma-rays from the blazar S5 0716+714

TL;DR

This paper reports the first detection of very high energy gamma-rays from the blazar S5 0716+714, revealing a possible correlation with optical activity and suggesting a structured jet model for its emission.

Contribution

First detection of VHE gamma-rays from S5 0716+714, with evidence of correlation to optical activity and implications for jet modeling.

Findings

Significant VHE gamma-ray detection with 5.8 sigma significance.

Gamma-ray flux correlates with optical high states.

Structured jet model better explains the data than simple models.

Abstract

The MAGIC collaboration reports the detection of the blazar S5 0716+714 z=0.31+-0.08 in very high energy gamma-rays. The observations were performed in November 2007 and in April 2008, and were triggered by the KVA telescope due to the high optical state of the object. An overall significance of the signal accounts to S =5.8sigma for 13.1 hours of data. Most of the signal S = 6.9sigma comes from the April 2008 data sample during a higher optical state of the object suggesting a possible correlation between the VHE gamma-ray and optical emissions. The differential energy spectrum of the 2008 data sample follows a power law with a photon index of Gamma = 3.45+-0.54_(stat)+-0.2_(syst), and the integral flux above 400GeV is at the level of 7.5+-2.2_(stat)+-2.3_(syst)*10^-12 cm^-2 s^-1 corresponding to a 9% Crab Nebula flux. Modeling of the broad band spectral energy distribution indicates that a structured jet model appears to be more promising in describing the available data than a simple one zone synchrotron self-Compton model.