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Abstract

Accurate and fast gravitational waveform (GW) models are essential to extract
information about the properties of compact binary systems that generate GWs.
Building on previous work, we present an extension of the NRTidal model for
binary neutron star (BNS) waveforms. The upgrades are: (i) a new closed-form
expression for the tidal contribution to the GW phase which includes further
analytical knowledge and is calibrated to more accurate numerical relativity
data than previously available; (ii) a tidal correction to the GW amplitude;
(iii) an extension of the spin-sector incorporating equation-of-state-dependent
finite size effects at quadrupolar and octupolar order; these appear in the
spin-spin tail terms and cubic-in-spin terms, both at 3.5PN. We add the new
description to the precessing binary black hole waveform model IMRPhenomPv2 to
obtain a frequency-domain precessing binary neutron star model. In addition, we
extend the SEOBNRv4_ROM and IMRPhenomD aligned-spin binary black hole waveform
models with the improved tidal phase corrections. Focusing on the new
IMRPhenomPv2_NRTidalv2 approximant, we test the model by comparing with
numerical relativity waveforms as well as hybrid waveforms combining tidal
effective-one-body and numerical relativity data. We also check consistency
against a tidal effective-one-body model across large regions of the BNS
parameter space.