Merger estimates for Kerr-Sen black holes

The advent of gravitational wave observation starts a new era of precision tests of gravitational theory. Estimates of black hole mergers should come from any well established gravitational theories, provided that the theory has not been ruled out by observations. We consider the low energy limit of heterotic string theory where the associated rotating and charged black holes are described by the Kerr-Sen solution. We investigate the approximate final spins and quasinormal modes of the black hole resulting from the merger process.