Gamma‐Ray Emission From the Old Nova GK Per

ABSTRACT

The rare event of an extremely bright explosion of a classical nova in 1901 gave birth to GK Per (Nova 1901). GK Per is one of the closest cataclysmic variables whose central binary consists of a magnetic white dwarf and a K2‐type subgiant. As the remnant of a classical nova, GK Per also has a shell that is observed from radio wavelength to x‐rays. The detection of synchrotron emission from the location of the reverse shock zone suggests that the shell of GK Per Nova may be a site where energetic electrons are produced by diffusive shock acceleration. These detections therefore make GK Per a candidate source of very‐high‐energy gamma‐ray emission. The results of observations of Nova Persei 1901 (GK Per) at very high energies with the SHALON mirror Cherenkov telescope are presented. SHALON has been detected TeV gamma‐ray emission from the classical nova GK Per for the first time. The gamma‐ray emission both from the central star binary system and from the shell of GK Per is extracted. The very‐high‐energy emission features of the GK Per shell, namely its hard power‐law spectrum and the presence of TeV emission in the shell regions of the reverse shock zone seen in x‐rays by Chandra, may be an evidence that the remnant of this classical nova evolves similarly to a supernova remnant at the early evolution stage.