N-body simulations of DGP and degravitation theories

We perform N-body simulations of theories with infinite-volume extra dimensions, such as the DvaliGabadadze-Porrati model and its higher-dimensional generalizations, where 4D gravity is mediated by massive gravitons. The longitudinal mode of these gravitons mediates an extra scalar force, which we model as a density-dependent modification to the Poisson equation. This enhances gravitational clustering, particularly on scales that have undergone mild nonlinear processing. While the standard nonlinear fitting algorithm of Smith et al. overestimates this power enhancement on nonlinear scales, we present a modified fitting formula that offers a remarkably good fit to our power spectra. Because of the uncertainty in galaxy bias, our results are consistent with precision power spectrum determinations from galaxy redshift surveys, even for graviton Compton wavelengths as small as 300 Mpc. Our model is sufficiently general that we expect it to capture the phenomenology of a wide class of related higher-dimensional gravity scenarios. Disciplines Physical Sciences and Mathematics | Physics Comments Suggested Citation: Khoury, J. and Wyman, M. (2009). "N-body simulations of DGP and degravitation theories." Physical Review D. 80, 064023. © 2009 The American Physical Society http://dx.doi.org/PhysRevD.80.064023 This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/53 N-body simulations of DGP and degravitation theories Justin Khoury and Mark Wyman Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2L 2Y5 (Received 25 March 2009; revised manuscript received 17 July 2009; published 17 September 2009) We perform N-body simulations of theories with infinite-volume extra dimensions, such as the DvaliGabadadze-Porrati model and its higher-dimensional generalizations, where 4D gravity is mediated by massive gravitons. The longitudinal mode of these gravitons mediates an extra scalar force, which we model as a density-dependent modification to the Poisson equation. This enhances gravitational clustering, particularly on scales that have undergone mild nonlinear processing. While the standard nonlinear fitting algorithm of Smith et al. overestimates this power enhancement on nonlinear scales, we present a modified fitting formula that offers a remarkably good fit to our power spectra. Because of the uncertainty in galaxy bias, our results are consistent with precision power spectrum determinations from galaxy redshift surveys, even for graviton Compton wavelengths as small as 300 Mpc. Our model is sufficiently general that we expect it to capture the phenomenology of a wide class of related higher-dimensional