Radiative Acceleration of Dense Circumstellar Material in Interacting Supernovae

Early-time light curves/spectra of some hydrogen-rich supernovae (SNe) give firm evidence on the existence confined, dense circumstellar matter (CSM) surrounding dying massive stars. We numerically and analytically study radiative acceleration CSM in such systems, where radiation is mainly powered by interaction between SN ejecta CSM. find that unshocked ahead shock larger for compact CSM, with velocities reaching up to $\sim 10^3\ {\rm km\ s^{-1}}$ a order $0.1\ M_\odot$ confined within 10^{15}$ cm. show dependence density helps us explain diversity velocity inferred from early spectra Type II SNe. For explosions even denser can affect dissipation strong collisionless shocks formed after breakout, which would non-thermal emission expected particle acceleration.