Coalescence Rates of Double Neutron Stars

Merger events of close double neutron stars (DNS) lie at the basis of a number of current issues in relativistic astrophysics, such as the indirect and possible direct detection of gravitational waves, the production of gamma-ray bursts at cosmological distances, and the origin of r-process elements in the universe. In assessing the importance or relevance of DNS coalescence to these issues, knowledge of the rate of coalescence in our Galaxy is required. In this paper, I review the current estimates of the DNS merger rate (theoretical and empirical) and discuss new ways to obtain limits on this rate using all information available at present.