Probing for the Origin of Binary Black Holes with Next-Generation Gravitational-Wave Observations

Abstract

Detections of gravitational wave (GW) from binary black holes, GW150914 and GW151226, suggest that the properties of the GW are consistent with general relativity. After the first detection, the origin of binary black holes has been discussed actively among researchers. However, there are still many possibilities for the formation scenario of binary black holes: the isolated binary model, the star cluster model, primordial black holes, and etc. In this article we discuss how we can discriminate the formation scenarios with current and future GW observations, particularly focusing on our recent proposals using orbital eccentricities and spatial clustering of binary black holes.