Radiative Acceleration of Dense Circumstellar Material in Interacting Supernovae

TL;DR

This paper investigates how radiation from supernova ejecta accelerates dense circumstellar material, explaining observed velocity diversity and influencing early shock emission in supernovae.

Contribution

It provides a combined numerical and analytical study of radiative acceleration of CSM, revealing its dependence on CSM properties and implications for supernova observations.

Findings

Acceleration can reach up to 1000 km/s for dense, compact CSM.

The CSM velocity diversity explains early spectral observations of Type II SNe.

Radiative acceleration impacts shock dissipation and early non-thermal emission.

Abstract

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. For explosions in even denser CSM, radiative acceleration can affect the dissipation of strong collisionless shocks formed after the shock breakout, which would affect early non-thermal emission expected from particle acceleration.