High-energy cosmic gamma rays from the `Single Source'

Some six years ago, we (Erlykin and Wolfendale, 1997) proposed the `single source model' in which a local, recent supernova remnant (SNR) was responsible for the `knee' in the cosmic ray (CR) energy spectrum at ~3PeV. Stimulated by the paper by Bhadra (2002), which drew attention to a possible gamma ray signature of this local remnant, we now study the situation for the local source and we conclude that, in contrast to Bhadra's conclusion, the non-observation of this remnant is understandable - at least using our SNR model. It is due to the fact that this SNR, being local, develops in the local hot interstellar medium (HISM) with its low density of gas and also being nearby it will be an extended source occupying up to 40$^\circ$ of the sky and thus indistinguishable from the background.