Gravitational waves from quasielliptic compact binaries in scalar-tensor theory to one-and-a-half post-Newtonian order

Trestini, David (2025) Gravitational waves from quasielliptic compact binaries in scalar-tensor theory to one-and-a-half post-Newtonian order. Classical and Quantum Gravity, 42 (15), [155016]. (doi:10.1088/1361-6382/adedf5).

Record type: Article

Abstract

The orbit-averaged fluxes of energy and angular momentum generated by a compact binary system of nonspinning particles are obtained in a popular class of massless scalar-tensor theories with first-and-a-half post-Newtonian (1.5PN) accuracy, i.e. 2.5PN accuracy beyond the leading −1PN dipolar radiation. The secular evolution of the orbital elements (frequency and eccentricity) are then also obtained with 1.5PN accuracy. Three technical advances were necessary to obtain these results: (i) the decomposition of the scalar dipole moment as a Fourier series at 1PN order, along with the other moments at Newtonian order, (ii) the derivation of the formula for the passage to the center-of-mass frame at 2.5PN, including a novel hereditary term arising from the contribution of the radiation, and (iii) the complete treatment of the memory-like term appearing in the angular momentum flux. Moreover, as a byproduct of this work, I revisit in the appendix the treatment in general relativity of the memory integral appearing at 2.5PN order in the angular momentum flux (Arun et al 2009 Phys. Rev. D 80 124018), and find that the spurious divergence in the initial eccentricity e ₁ found there is cured by a careful split between AC and DC terms.

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