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Abstract

The subsequent observing runs of the advanced gravitational-wave detector
network will likely provide us with various gravitational-wave observations of
binary neutron star systems. For an accurate interpretation of these
detections, we need reliable gravitational-wave models. To test and to point
out how existing models could be improved, we perform a set of high-resolution
numerical-relativity simulations for four different physical setups with mass
ratios $q$ = $1.25$, $1.50$, $1.75$, $2.00$, and total gravitational mass $M =
2.7M_\odot$ . Each configuration is simulated with five different resolutions
to allow a proper error assessment. Overall, we find approximately 2nd order
converging results for the dominant $(2,2)$, but also subdominant $(2,1)$,
$(3,3)$, $(4,4)$ modes, while, generally, the convergence order reduces
slightly for an increasing mass ratio. Our simulations allow us to validate
waveform models, where we find generally good agreement between
state-of-the-art models and our data, and to prove that scaling relations for
higher modes currently employed for binary black hole waveform modeling also
apply for the tidal contribution. Finally, we also test if the current NRTidal
model to describe tidal effects is a valid description for high-mass ratio
systems. We hope that our simulation results can be used to further improve and
test waveform models in preparation for the next observing runs.