High accuracy post-Newtonian and numerical relativity comparisons involving higher modes for eccentric binary black holes and a dominant mode eccentric inspiral-merger-ringdown model

Spherical harmonic modes of gravitational waveforms for inspiraling compact binaries in eccentric orbits from post-Newtonian (PN) theory accurate to third post-Newtonian order and those extracted from numerical relativity (NR) simulations for binary black holes (BBHs) are compared. We combine results from the two approaches (PN and NR) to construct time-domain hybrid waveforms that describe the complete evolution of BBH mergers through inspiral-merger-ringdown (IMR) stages. These hybrids are then used in constructing a fully analytical dominant mode (ℓ=2, |m|=2) eccentric IMR model. A simple extension to a multimode model based on this dominant mode model is also presented. Overlaps with quasicircular IMR waveform models including the effect of higher modes, maximized over a time and phase shift, hint at the importance (mismatches>1%) of including eccentricity in gravitational waveforms when analyzing BBHs lighter than ∼80 M⊙, irrespective of the binary's eccentricity (as it enters the LIGO bands) or mass ratio. Combined impact of eccentricity and higher modes seems to become more apparent through smaller overlaps with increasing inclination angles and mass ratios. Additionally, we show that the state-of-the-art quasicircular models including the effect of higher modes will not be adequate in extracting source properties for signals with initial eccentricities e0≳0.1.