Search for TeV gamma-rays from the active radio galaxy centaurus a with CANGAROO-III

Abstract

We have observed the giant radio galaxy CentaurusA (Cen A) in the TeV energy region using the CANGAROOIII stereoscopic system. The system has been in operation since 2004 and is an array of four Imaging Atmospheric Cherenkov Telescopes (IACT) with about a 100 m spacing. The observations were carried out between March and April 2004. In total 20-hour data were obtained. No statistically significant gamma-ray signal has been found above 530 GeV and we obtain an integral flux upper limit of 3.2 × 10-12 cm10 -2 see10-1 (2-αlevel). This upper limit is less than 7 % of the gamma-ray flux from the Crab nebula. Although some groups reported detections of Cen A in the past, we give upper limits more than one-order of magnitude lower for this object. Show more