Detection of diffuse TeV gamma-ray emission from the nearby starburst galaxy NGC 253

摘要

We report TeV gamma-ray observations of the nearby normal spiral galaxy NGC 253.NGC 253 is one of the nearest starburst galaxies,at a distance of ~2.5 Mpc.This relative closeness,coupled with the high star formation rate in the galaxy,make it a good candidate TeV gamma-ray source.Observations were carried out in 2000 and 2001 with the CANGAROO-II 10m imaging atmospheric Cherenkov telescope.TeV gamma-ray emission is detected at the ~ 11sigma level with a flux of (7.8 +-2.5) x 10~(-12)cm~(-2)sec~(-1) at energies >0.5 TeV.The data indicate that the emission region is broader than the point spread function of our telescope.