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General Relativity and Quantum Cosmology, gr-qc
Abstract:
In this paper, we test the performance of templates in detection and
characterization of Spin-orbit resonant (SOR) binaries. We use precessing
SEOBNRv3 waveforms as well as {\it four} numerical relativity (NR) waveforms to
model GWs from SOR binaries and filter them through IMRPhenomD, SEOBNRv4
(non-precessing) and IMRPhenomPv2 (precessing) approximants. We find that
IMRPhenomD and SEOBNRv4 recover only $\sim70\%$ of injections with fitting
factor (FF) higher than 0.97 (or 90\% of injections with ${\rm FF}
>0.9$).However, using the sky-maxed statistic, IMRPhenomPv2 performs
magnificently better than their non-precessing counterparts with recovering
$99\%$ of the injections with FFs higher than 0.97. Interestingly, injections
with $\Delta \phi = 180^{\circ}$ have higher FFs ($\Delta \phi$ is the angle
between the components of the black hole spins in the plane orthogonal to the
orbital angular momentum) as compared to their $\Delta \phi =0^{\circ}$ and
generic counterparts. This implies that we will have a slight observation bias
towards $\Delta \phi=180^{\circ}$ SORs while using non-precessing templates for
searches. All template approximants are able to recover most of the injected NR
waveforms with FFs $>0.95$. For all the injections including NR, the error in
estimating chirp mass remains below $<10\%$ with minimum error for $\Delta \phi
= 180^{\circ}$ resonant binaries. The symmetric mass ratio can be estimated
with errors below $15\%$. The effective spin parameter $\chi_{\rm eff}$ is
measured with maximum absolute error of 0.13. The in-plane spin parameter
$\chi_p$ is mostly underestimated indicating that a precessing signal will be
recovered as a relatively less precessing signal. Based on our findings, we
conclude that we not only need improvements in waveform models towards
precession and non-quadrupole modes but also better search strategies for
precessing GW signals.
