Model estimate of energy and efficiency in Extended Emission from a black hole remnant in GW170817

A MatLab code producing a model estimate of energy and efficiency in Extended Emission produced in black hole spin-down against a thick torus. It uses numerical integration of the equations of suspended accretion with effective mean values of the mass and radius of the torus, the latter correlated to the radius of the ISCO by a constant K. The results show an energy output E_gw ~ 3.6-4.3%M_Solarc² in gravitational-wave emission, where c is the velocity of light, for initial frequencies 600-700 Hz reported in van Putten, M.H.P.M., & Della Valle, M., 2019, MNRAS, 482, L46. It is powered by the energy E_J in angular momentum J of a 3M_Solar black hole remnant inherited from a merged neutron star in the immediate aftermath of GW170817 for canonical values of the initial dimensionless spin parameter a/M. Use of effective constants provides estimates of potential total output and net efficiency in converting E_J to E_gw without providing detailed temporal evolution of gravitational-wave strain and frequency.