Compact binary systems in scalartensor gravity. II. Tensor gravitational waves to second postNewtonian order
Abstract
We derive the tensor gravitational waveform generated by a binary of nonspinning compact objects (black holes or neutron stars) in a general class of scalartensor theories of gravity. The waveform is accurate to second postNewtonian order beyond the leading order quadrupole approximation. We use the direct integration of the relaxed Einstein equations formalism, appropriately adapted to scalartensor theories, along with previous results for the equations of motion in these theories. The selfgravity of the compact objects is treated with an approach developed by Eardley. The scalar field causes deviations from the general relativistic waveform that depend only on a small number of parameters. Among the effects of the scalar field are new hereditary terms which depend on the past history of the source. One of these, a dipoledipole coupling, produces a zerofrequency "gravitationalwave memory" equivalent to the Christodoulou memory of general relativity. In the special case of two black holes, the waveform reduces to the general relativistic waveform. For a mixed (black holeneutron star) system, the waveform is identical to that of Einstein's theory to first postNewtonian order, with deviations at higher order depending only on a single parameter. The behavior in these cases matches that found for the equations of motion.
 Publication:

Physical Review D
 Pub Date:
 April 2014
 DOI:
 10.1103/PhysRevD.89.084014
 arXiv:
 arXiv:1310.3320
 Bibcode:
 2014PhRvD..89h4014L
 Keywords:

 04.30.Db;
 04.25.Nx;
 04.50.Kd;
 Wave generation and sources;
 PostNewtonian approximation;
 perturbation theory;
 related approximations;
 Modified theories of gravity;
 General Relativity and Quantum Cosmology
 EPrint:
 44 pages