The Highest Energy Emission Detected by EGRET from Blazars

Abstract

Published EGRET spectra from blazars extend only to 10 GeV, yet EGRET has detected approximately 2000 gamma-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy gamma-rays for associations with the EGRET and TeV detected blazars. Because the point spread function of EGRET improves with energy, only ~2 gamma-rays are expected to be positionally coincident with the 80 blazars searched, yet 23 gamma-rays were observed. This collection of > 10 GeV sources should be of particular interest due to the improved sensitivity and lower energy thresholds of ground-based TeV observatories. One of the blazars, RGB0509+056, has the highest energy gamma-rays detected by EGRET from any blazar with 2 > 40 GeV, and is a BL Lac type blazar with unknown redshift.