Luminous Late-time Radio Emission from Supernovae Interacting with Circumbinary Material

Abstract Numerous core-collapse supernovae (CCSNe) exhibit signatures of interaction with circumstellar material (CSM). Bright radio emission years after the supernova (SN) is one such indication of dense CSM at large distances from the star, which may be generated via binary interactions. In this work, we use forward modeling to study the radio emission produced by the interaction between the SN ejecta and CSM formed by nonconservative stable mass transfer from stripped-envelope stars in short-period binaries. The donors are among the likely progenitors of hydrogen-poor CCSNe that significantly expand 10 3 –10 4 yr before core collapse, with companions that best represent low-mass compact objects. We identify that nonconservative stable mass transfer from lower-mass stripped stars can create a detached shell-like CSM, whereas for our higher-mass stars, the CSM is wind-like. In our models, mass-transfer rates of ∼10 −4 M ⊙ yr −1 lead to dense CSM extending to ∼10 18 cm. The predicted radio emission is luminous at late times, reaching L ν ∼ 10 26 –10 29 erg s −1 Hz −1 at years to decades after core collapse, which is as bright as late-time radio emission observed for a sample of hydrogen-poor SNe. However, the light curves of events with early-time data show more complex behavior in the weeks to months after core collapse. We qualitatively demonstrate that similar early-time emission can manifest for a CSM that is accelerated to speeds of ∼10 3 km s −1 upon ejection, as well as for different viewing angles in the case of an asymmetric CSM distribution.