[1108.1826] Testing General Relativity with LISA including Spin Precession and Higher Harmonics in the Waveform

Authors: Cédric Huwyler, Antoine Klein, Philippe Jetzer

Date: 8 Aug 2011

Abstract: In this paper, we compute the accuracy at which the planned space-based gravitational wave detector LISA will be able to observe deviations from General Relativity. To do so, we introduce six correction parameters that account for modified gravity in the second post-Newtonian gravitational wave phase for inspiralling supermassive black hole binaries with spin precession on quasi-circular orbits. The precession of the spins and the angular momentum modulate the gravitational waveform, resulting in additional structure which could reduce correlations in the parameter space and increase the detection accuracy of the alternative theory parameters. Also, the use of higher harmonics could create further structure and increase the time during which the signal lasts in the frequency window of LISA. In order to find error distributions for the alternative theory parameters, we use the Fisher information formalism and carry out Monte Carlo simulations for 17 different binary black hole mass configurations in the range 10ˆ5 Msun < M < 10ˆ8 Msun with 10ˆ3 randomly distributed points in the parameter space each, using the full (FWF) and restricted (RWF) version of the gravitational waveform. We find that the binaries can roughly be separated into two groups: one with low (\precsim 10ˆ7 Msun) and one with high total masses (\succsim 10ˆ7 Msun). The RWF errors on the alternative theory parameters are two orders of magnitude higher than the FWF errors for high-mass binaries while almost comparable for low-mass binaries. Due to dilution of the available information, the accuracy of the binary parameters is reduced by factors of a few, except for the luminosity distance which is affected more seriously in the high-mass regime. As an application, we compute an optimal lower bound on the graviton mass which is increased by a factor of ~1.5 when using the FWF.

abs pdf

Aug 10, 2011

1108.1826 (/preprints)
2011-08-10, 09:06 [edit]

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