Population Properties of Binary Black Holes with Eccentricity

Title: Population Properties of Binary Black Holes with Eccentricity

Highlight: Two of my students recently led a study which reanalyzed most gravitational-wave observations to date, looking for clear indications that some events exhibit signs of eccentricity. Previous studies have suggested that some events might be eccentric (our own included!). However, accidents happen. In this work, we do a first-of-its-kind population study, self-consistently recovering all of the properties of the BBH population using a parametric model that accounts for eccentricity. (This required, among other things, reanalyzing every event using an eccentric waveform model. Natalie’s paper with details on that process will be out soon!). Sad trombone: so far, despite some events showing some indications consistent with eccentricity, with the waveform models we used we don’t find compelling evidence of a significantly eccentric population: eccentricities are small. While consistent with expectations now, eventually as the population increases, we’ll increasingly probe more and more unlikely encounters… so watch this space!

For experts: Our use of an aligned-spin model prohibits us from disentangling eccentricity and precession.