The r-process in neutron star mergers and the radioactive energies

The discovery of a neutron star merger as the source of gravitational wave signals (GW170817) provides us with clues to understanding the astrophysical origin of the r-process elements. However, a satisfactory model of mergers to account for this event is still missing. Moreover, no evidence of the production of the r-process elements heavier than lanthanides, such as gold and uranium, was obtained from the observations of the kilonova (an electromagnetic counterpart of GW170817). I will discuss the radioactive energies from decaying r-process nuclei as to diagnose the production of heavy r-process elements in GW170817 and in the future merger events. The current status of the merger models and galactic chemical evolution study relevant to the r-process also will be presented.