Gravitational waves (GWs) provide a revolutionary tool to investigate yet unobserved astrophysical objects. Especially the first stars, which are believed to be more massive than present-day stars, might be indirectly observable via the merger of their compact remnants. I present our self-consistent, cosmologically representative, semi-analytical model to simulate the formation of the first stars and to track the binary stellar evolution of the individual systems until the coalescence of the compact remnants. Owing to their higher masses, the remnants of primordial stars produce strong GW signals, even if their contribution in number is relatively small. We find a probability of ~1% that GW150914 is of primordial origin. We estimate that aLIGO will detect roughly 1 primordial BH-BH merger per year for the final design sensitivity, although this rate depends sensitively on the primordial initial mass function. Turning this around, the detection of black hole mergers with a total binary mass of ~300Msun would enable us to constrain the primordial initial mass function.
Host: Alex Ji