Testing gravity with gravitational wave source counts. (15th July 2016)

• Record Type: Journal Article
• Authors: Calabrese, Erminia; Battaglia, Nicholas; Spergel, David N
• Is Part Of: Classical and quantum gravity. Volume 33:Number 16(2016:Aug.)
• Publication Date: 2016-07-15
• Subjects: gravitational radiation -- gravity waves -- signal-to-noise ratio; Quantum gravity -- Periodicals; Gravitation -- Periodicals; Relativity (Physics) -- Periodicals; Space and time -- Periodicals; Periodicals; 521.1
• DOI: 10.1088/0264-9381/33/16/165004
• Languages: English
• ISSNs: 0264-9381

Abstract

Abstract: We show that the gravitational wave source counts distribution can test how gravitational radiation propagates on cosmological scales. This test does not require obtaining redshifts for the sources. If the signal-to-noise ratio ( ρ ) from a gravitational wave source is proportional to the strain then it falls as R − 1, thus we expect the source counts to follow d N / d ρ ∝ ρ − 4 . However, if gravitational waves decay as they propagate or propagate into other dimensions, then there can be deviations from this generic prediction. We consider the possibility that the strain falls as R − γ, where γ = 1 recovers the expected predictions in a Euclidean uniformly-filled Universe, and forecast the sensitivity of future observations to deviations from standard General Relativity. We first consider the case of few objects, seven sources, with a signal-to-noise from 8 to 24, and impose a lower limit on γ, finding γ > 0.33 at 95% confidence level. The distribution of our simulated sample is very consistent with the distribution of the trigger events reported by Advanced LIGO. Future measurements will improve these constraints: with 100 events, we estimate that γ can be measured with an uncertainty of 15%. We generalize the formalism to account for a range of chirp masses and the possibility that the signal falls as exp ( − R / R 0 ) / R γ .