On the use and interpretation of signal-model indistinguishability measures for gravitational-wave astronomy

Understand

The difference ("mismatch") between two gravitational-wave (GW) signals is often used to estimate the signal-to-noise ratio (SNR) at which they will be distinguishable in a measurement or, alternatively, when the errors in a signal model will lead to biased measurements.

• It is well known that the standard approach to calculate this "indistinguishability SNR" is too conservative: a model may fail the criterion at a given SNR, but not necessarily incur a biased measurement of any individual parameters.
• This problem can be solved by taking into account errors orthogonal to the model space (which therefore do not induce a bias), and calculating indistinguishability SNRs for individual parameters, rather than the full $N$-dimensional parameter space.
• We illustrate this approach with the simple example of aligned-spin binary-black-hole signals, and calculate accurate estimates of the SNR at which each parameter measurement will be biased.