Is the Giant Radio Galaxy M87 a TeV Gamma-Ray Emitter?
Abstract
For the first time an excess of photons above an energy threshold of 730 GeV from the giant radio galaxy M87 has been measured at a significance level above 4 sigma. The data have been taken during the years 1998 and 1999 with the HEGRA stereoscopic system of 5 imaging atmospheric Cherenkov telescopes. The excess of 107.4 +- 26.8 events above 730 GeV corresponds to an integral flux of 3.3% of the Crab flux or N_gamma(E > 730 GeV) = (0.96 +- 0.23) * 10^(-12) phot.cm^(-2)s^(-1). M87 is located at the center of the Virgo cluster of galaxies at a relatively small redshift of z = 0.00436 and is a promising candidate among the class of giant radio galaxies for the emission of TeV gamma-radiation. The detection of TeV gamma-rays from M87 -- if confirmed -- would establish a new class of extragalactic source in this energy regime since all other AGN detected to date at TeV energies are BL Lac type objects.
Cite
@article{arxiv.astro-ph/0302155,
title = {Is the Giant Radio Galaxy M87 a TeV Gamma-Ray Emitter?},
author = {HEGRA Collaboration and F. Aharonian and A. Akhperjanian and M. Beilicke},
journal= {arXiv preprint arXiv:astro-ph/0302155},
year = {2010}
}
Comments
5 pages, 3 figures, refereed version, corrected calculation of energy flux