Radiative Acceleration of Dense Circumstellar Material in Interacting Supernovae

Understand

Early-time light curves/spectra of some hydrogen-rich supernovae (SNe) give firm evidence on the existence of confined, dense circumstellar matter (CSM) surrounding dying massive stars.

• We numerically and analytically study radiative acceleration of CSM in such systems, where the radiation is mainly powered by the interaction between the SN ejecta and the CSM.
• We find that the acceleration of the unshocked dense CSM ahead of the shock is larger for massive and compact CSM, with velocities reaching up to $\sim 10^3\ {\rm km\ s^{-1}}$ for a CSM of order $0.1\ M_\odot$ confined within $\sim 10^{15}$ cm.
• We show that the dependence of the acceleration on the CSM density helps us explain the diversity of the CSM velocity inferred from the early spectra of some Type II SNe.