Interstellar protons toward γ-ray SNRs

It is presented that two young TeV γ-ray SNRs, RX J1713.7–3946 and RX J0852.0–4622, show good spatial correspondence between the TeV γ-rays and the interstellar protons. The good spatial correspondence provides a support for the hadronic origin of the γ-rays in these SNRs. It is emphasized that not only molecular hydrogen but also atomic hydrogen play a role as targets for the cosmic ray protons. The clumpy distribution of the interstellar medium (ISM) protons is crucial in producing the hadronic γ-rays with suppression of thermal X-rays, whereas models with uniform ISM distribution are not viable.