Discovery of a very high energy gamma-ray signal from the 3C 66A/B region

TL;DR

The MAGIC telescope detected a high-energy gamma-ray source in the 3C 66A/B region, likely associated with the radio galaxy 3C 66B, revealing a new gamma-ray emitter with a specific energy spectrum.

Contribution

This is the first detection of very high energy gamma-ray emission from the 3C 66A/B region, identifying a new gamma-ray source and characterizing its spectrum.

Findings

Detected gamma-ray source MAGIC J0223+430 above 150 GeV

Spectrum follows a power law with photon index -3.10

No significant variability observed during the observation period

Abstract

The MAGIC telescope observed the region around the distant blazar 3C 66A for 54.2 h in 2007 August-December. The observations resulted in the discovery of a gamma-ray source at energies above 150 GeV centered at celestial coordinates RA=2h23m12s and DEC=43deg0.7' (MAGIC J0223+430), coinciding with the nearby radio galaxy 3C 66B. A possible association of the excess with the blazar 3C 66A is discussed. The energy spectrum of MAGIC J0223+430 follows a power law with a normalization of (1.7+-0.3_(stat)+-0.6_(syst)) 10^(-11) TeV^(-1)cm^(-2)s^(-1) at 300 GeV and a photon index Gamma=-3.10+-0.31_(stat)+-0.2_(syst). No significant variability of the signal was found during the observation period.