Variance of gravitational-wave populations

Say we live in another Universe, and in that Universe of course we are still collecting gravitational-wave data. Those data will kind of look like ours, but not quite, they’ll be another realization of the same statistical process. What I’m trying to say is that the astrophysics we infer from GW data is, of course, constrained by the actual data we are collecting; this is equivalent to saying that there is an intrinsic variance due to the finite size of our event catalog. (If I could have infinitely many events, GW data from all parallel Universes would look the same!)

Here we try to quantify this variance using statistical bootstrapping, and it turns out it’s not negligible at all. Some technical details include bootstrapping over both events and sensitivity injections to avoid messing up selection effects. This is work by Alessia Corelli, a current MSc student with me (who managed to submit a paper even before graduating!) together with our friends in Nottingham, Matt and Cecilia.

A. Corelli, D. Gerosa, M. Mould, C. M. Fabbri.
arXiv:2603.00239 [astro-ph.HE].