On the Identification of Exotic Compact Binaries with Gravitational Waves: a Phenomenological approach

Gravitational wave (GW) astronomy has been hailed as a gateway to discovering unexpected phenomena in the universe. Over the last decade there have been more than two hundred GW observations of compact-binary mergers. While these signals are largely consistent with mergers of binary black holes, binary neutron stars, or black hole-neutron star systems, some events suggest the intriguing possibility of binaries involving exotic compact objects (ECOs). Identifying and characterising an ECO merger would require accurate ECO waveform models. Using large numbers of numerical relativity simulations to develop customised models for ECO mergers akin to those used for binary black holes, would be not only computationally expensive but also challenging due to the limited understanding of the underlying physics. Alternatively, key physical imprints of the ECO on the inspiral or merger could in principle be incorporated phenomenologically into waveform models. I will present an application of this idea to assess the detectability and distinguishability of ECO mergers, and discuss a phenomenological approach that can iteratively incorporate features of ECO mergers, laying the groundwork for an effective exotic compact object identifier in compact binary coalescences. I will also discuss results inferred from the data for the GW event GW150914, using Bayesian parameter estimation within this framework, and present first direct estimates of compactness from a compact binary merger.