## [1006.1632] Notes on the integration of numerical relativity waveforms

Authors: Christian Reisswig, Denis Pollney

Date: 8 Jun 2010

Abstract: A primary goal of numerical relativity is to provide estimates of the wave strain, $h$, from strong gravitational wave sources, to be used in detector templates. The simulations, however, typically measure waves in terms of gauge resilient quantities, such as the Weyl curvature component, $\psi_4$. Transforming to the strain requires integration of the measured variable twice in time. There are a number of fundamental difficulties which can arise from integrating finite length, discretely sampled and noisy data streams. These issues are related to the post-processing of the data, and thus independent of the characteristics of the original simulation, such as gauge or numerical method used. In particular, secular drifts in integrated waveforms have been observed empirically, but can also be studied with simple analytic models. We demonstrate that regardless of the nature of the original simulation, a degree of uncertainty will always be present in a strain which is calculated by integration. We suggest, however, a simple procedure for integrating numerical waveforms in the frequency domain, which is effective at strongly reducing spurious secular drifts in the resulting strain.

#### Jun 10, 2010

1006.1632 (/preprints)
2010-06-10, 14:03