Speaker
Description
We improve and generalize to all multipoles the factorization and resummation approach of Nagar and Shah,designed to improve the strong-field behavior of the post-Newtonian (PN) residual waveform amplitudes $f_{\ell m}$'s entering the effective-one-body, circularized, gravitational waveform for spinning coalescing binaries. For a test-particle orbiting a Kerr black hole, each multipolar amplitude is truncate at relative 6~post Newtonian (PN) order, both for the orbital and spin factors. By taking a certain Pad\'e approximant of the orbital factor in conjuction with the inverse Taylor (iResum) representation of the spin factor, it is possible to push the analytical/numerical agreement of the energy flux at the level of $5\%$ at the last-stable-orbit for a spinning black hole with dimensionless spin parameter $+0.99$.
When the procedure is generalized to comparable-mass binaries, each orbital factor is
kept at relative $3^{+3}$PN order, i.e. the globally 3PN-accurate comparable-mass terms
are hybridized with higher PN test-particle terms up to 6PN relative order in each mode.
The same Pad\'e resummation is used for continuity. By contrast, the spin factor is only
kept at the highest comparable-mass PN-order currently available. We illustrate that the
consistency between different truncations in the spin content of the waveform amplitudes
is more marked in the resummed case than when using the standard Taylor-expanded form.
We finally introduce a method to consistently hybridize comparable-mass and test-particle
information {\it also} in the presence of spin.
The improved, factorized and resummed, multipolar waveform amplitudes presented
here are expected to set a new standard for effective-one-body-based
gravitational waveform models.
