Dynamical ejecta synchrotron emission as a possible contributor to the changing behaviour of GRB170817A afterglow

ABSTRACT Over the past 3 yr, fading non-thermal emission from GW170817 remained generally consistent with afterglow powered by synchrotron radiation produced interaction of structured jet ambient medium. Recent observations Hajela et al. indicate change in temporal and spectral behaviour X-ray band. We show that new are compatible emergence a component due to fast tail dynamical ejecta ab-initio binary neutron star merger simulations. This provides avenue constrain parameters. Specifically, we find equal mass models soft equations state (EOSs) high-mass ratio stiff EOSs disfavoured as they typically predict afterglows peak too early explain recent observations. Moderate stiffness models, instead, tend be good overall agreement data.