Extreme- and intermediate-mass ratio inspirals in dynamical Chern-Simons modified gravity

Journal Article · Tue Sep 15 00:00:00 EDT 2009 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.80.064006· OSTI ID:21322719

Sopuerta, Carlos F ^[1]; Yunes, Nicolas ^[2]

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1. Institut de Ciencies de l'Espai (CSIC-IEEC), Facultat de Ciencies, Campus UAB, Torre C5 parells, Bellaterra, 08193 Barcelona (Spain)
2. Physics Department, Princeton University, Princeton, New Jersey 08544 (United States)

Chern-Simons modified gravity is a four-dimensional, effective theory that descends both from string theory and loop quantum gravity, and that corrects the Einstein-Hilbert action by adding the product of a scalar field and the parity-violating, Pontryagin density. The Chern-Simons modification deforms the gravitational field of spinning black holes, which is now described by a modified Kerr geometry whose multipole moments deviate from the Kerr ones only at the fourth multipole l=4. This paper investigates possible signatures of this theory in the gravitational-wave emission produced in the inspiral of stellar compact objects into massive black holes, both for intermediate- and extreme-mass ratios. We use the semirelativistic approximation, where the trajectory of the small compact object is modeled via geodesics of the massive black hole geometry, while the gravitational waveforms are obtained from a multipolar decomposition of the radiative field. The main Chern-Simons corrections to the waveforms arise from modifications to the geodesic trajectories, which in turn are due to changes to the massive black hole geometry, and manifest themselves as an accumulating dephasing relative to the general relativistic case. We also explore the propagation and the stress-energy tensor of gravitational waves in this theory, using the short-wavelength approximation. We find that, although this tensor has the same form as in general relativity, the energy and angular momentum balance laws are indeed modified through the stress-energy tensor of the Chern-Simons scalar field. These balance laws could be used to describe the inspiral through adiabatic changes in the orbital parameters, which in turn would enhance the dephasing effect. Gravitational-wave observations of intermediate- or extreme-mass-ratio inspirals with advanced ground detectors or with the Laser Interferometer Space Antenna could use such dephasing to test the dynamical theory to unprecedented levels, thus beginning the era of gravitational-wave tests of effective quantum gravity theories.

• OSTI ID: 21322719
• Journal Information: Physical Review. D, Particles Fields, Vol. 80, Issue 6; Other Information: DOI: 10.1103/PhysRevD.80.064006; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR MOMENTUM
APPROXIMATIONS
BLACK HOLES
CORRECTIONS
DECOMPOSITION
DENSITY
EMISSION
FOUR-DIMENSIONAL CALCULATIONS
GENERAL RELATIVITY THEORY
GEODESICS
GRAVITATION
GRAVITATIONAL FIELDS
GRAVITATIONAL WAVES
INTERFEROMETERS
KERR METRIC
MASS
MODIFICATIONS
QUANTUM FIELD THEORY
QUANTUM GRAVITY
RELATIVISTIC RANGE
SCALAR FIELDS
SPACE
STRING MODELS
STRING THEORY
TRAJECTORIES
WAVE FORMS
WAVE PROPAGATION
WAVELENGTHS