A Collapsar Origin for GRB 211211A Is (Just Barely) Possible

Gamma-ray bursts (GRBs) have historically been divided into two classes. Short-duration GRBs are associated with binary neutron-star mergers (NSMs), while long-duration connected to a subset of core-collapse supernovae (SNe). GRB 211211A recently made headlines as the first burst purportedly generated by an NSM. The evidence for NSM origin was excess optical and near-infrared emission consistent kilonova observed after gravitational wave-detected GW170817. Kilonovae derive their unique electromagnetic signatures from properties heavy elements synthesized rapid neutron capture (the r-process) following merger. Recent simulations suggest that "collapsar" SNe trigger long may also produce r-process elements. While observations its afterglow ruled out SN typical those follow GRBs, unusual collapsar could explain both duration r-process-powered in afterglow. We use semianalytic radiation transport modeling evaluate low-mass collapsars progenitors 211211A-like events. compare suite models afterglow-subtracted followed 211211A, find best agreement high kinetic energies unexpected pattern Ni-56 enrichment. discuss how explosions such ejecta, distinct our predictions more straightforward models. show radio can distinguish between kilonovae massive ejecta we consider here.