2009/09/02 by Scott F. Daniel
Physics and Astronomy · #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph.CO
paper · pdf · doi:10.1103/physrevd.80.083520
published as Phys.Rev.D80:083520,2009 · 25 pages, 9 figures
arxiv created 2009/09/02 · openalex publication_date 2009/10/28 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Cosmological departures from general relativity offer a possible explanation for the cosmic acceleration. To linear order, these departures (quantified by the model-independent parameter \ensuremath\varpi, referred to as a ``gravitational slip'') amplify or suppress the growth of structure in the universe relative to what we would expect to see from a general relativistic universe lately dominated by a cosmological constant. As structures collapse and become more dense, linear perturbation theory is an inadequate descriptor of their behavior, and one must extend calculations to nonlinear order. If the effects of gravitational slip extend to these higher orders, we might expect to see a signature of \ensuremath\varpi in the bispectrum of galaxies distributed on the sky. We solve the equations of motion for nonlinear perturbations in the presence of gravitational slip and find that, while there is an effect on the bispectrum, it is too weak to be detected with present galaxy surveys. We also develop a formalism for incorporating scale dependence into our description of gravitational slip.