Mass-transferring binary stars as progenitors of interacting hydrogen-free supernovae

Context. Stripped-envelope supernovae (SNe) are hydrogen-poor transients produced at the end of the life of massive stars that have previously lost most or all of their hydrogen-rich envelope. The progenitors of most stripped-envelope SNe are thought to be donor stars in mass-transferring binary systems that were stripped of their hydrogen-rich envelopes some 106 yr before core collapse. A subset of the stripped-envelope SNe exhibit spectral and photometric features indicative of early, intense interactions between their ejecta and nearby circumstellar material (CSM) occurring within days or weeks of the explosion. Aims. We examine whether Roche lobe overflow during or shortly before core collapse in massive binary systems can produce the CSM inferred from the observations of interacting H-poor SNe. Methods. We selected 44 models from a comprehensive grid of detailed binary evolution models that are representative of the subset in which the mass donors are hydrogen-free and explode while transferring mass to a main-sequence companion. We characterized the properties of the pre-SN stellar models and of the material surrounding the binary at the time of the SN. Results. We find that in these models, mass transfer starts less than ∼20 kyr before and often continues until the core collapse of the donor star. Up to 0.8 M⊙ of hydrogen-free material are removed from the donor star during this phase, and a large fraction may be lost from the binary system and produce He-rich circumbinary material. We explored plausible assumptions for its spatial distribution at the time of explosion. When assuming that the CSM accumulates in a circumbinary disk, we found qualitative agreement with the SN and CSM properties inferred from the observed Type Ibn SNe and to a lesser extent with constraints from Type Icn SNe. Considering the birth probabilities of our mass transferring stripped envelope SN progenitor models, we find that they may produce up to ∼10% of all stripped-envelope SNe. Conclusions. The generic binary channel proposed in this work can qualitatively account for the observed key properties and the observed rate of interacting H-poor SNe. Models for the evolution of the circumbinary material and for the spectral evolution of exploding progenitors from this channel are needed to further test its significance.