Gravitational radiation from compact binaries in scalar-tensor gravity

• Main Author: Lang, Ryan N
• Format: Journal Article
• Language: English
• Published: 05-08-2014
• Subjects: Physics - General Relativity and Quantum Cosmology
• DOI: 10.48550/arxiv.1408.0860

General relativity (GR) has been extensively tested in the solar system and
in binary pulsars, but never in the strong-field, dynamical regime. Soon,
gravitational-wave (GW) detectors like Advanced LIGO and eLISA will be able to
probe this regime by measuring GWs from inspiraling and merging compact
binaries. One particularly interesting alternative to GR is scalar-tensor
gravity. We present progress in the calculation of second post-Newtonian (2PN)
gravitational waveforms for inspiraling compact binaries in a general class of
scalar-tensor theories. The waveforms are constructed using a standard GR
method known as "direct integration of the relaxed Einstein equations,"
appropriately adapted to the scalar-tensor case. We find that differences from
general relativity can be characterized by a reasonably small number of
parameters. Among the differences are new hereditary terms which depend on the
past history of the source. In one special case, binary black hole systems, we
find that the waveform is indistinguishable from that of general relativity. In
another, mixed black hole-neutron star systems, all differences from GR can be
characterized by only a single parameter.