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Published December 2009 | public
Journal Article

Cosmological simulations of normal-branch braneworld gravity

Abstract

We introduce a cosmological model based on the normal branch of Dvali-Gabadadze-Porrati (DGP) braneworld gravity with a smooth dark energy component on the brane. The expansion history in this model is identical to ΛCDM, thus evading all geometric constraints on the DGP crossover scale r_c. This well-defined model can serve as a first approximation to more general braneworld models whose cosmological solutions have not been obtained yet. We study the formation of large-scale structure in this model in the linear and nonlinear regime using N-body simulations for different values of r_c. The simulations use the code presented in 25 and solve the full nonlinear equation for the brane-bending mode in conjunction with the usual gravitational dynamics. The brane-bending mode is attractive rather than repulsive in the DGP normal branch, hence the sign of the modified gravity effects is reversed compared to those presented in 25. We compare the simulation results with those of ordinary ΛCDM simulations run using the same code and initial conditions. We find that the matter power spectrum in this model shows a characteristic enhancement peaking at k ~ 0.7h/Mpc. We also find that the abundance of massive halos is significantly enhanced. Other results presented here include the density profiles of dark matter halos, and signatures of the brane-bending mode self-interactions (Vainshtein mechanism) in the simulations. Independently of the expansion history, these results can be used to place constraints on the DGP model and future generalizations through their effects on the growth of cosmological structure.

Additional Information

© 2009 The American Physical Society. Received 5 October 2009; published 3 December 2009. We would like to thank W. Hu, K. Koyama, R. Scoccimarro, M. Wyman, and J. Khoury for discussions and insightful comments. We thank the Aspen Center for Physics where part of this work was completed for hospitality. The simulations used in this work have been performed on the Joint Fermilab-KICP Supercomputing Cluster, supported by grants from Fermilab, Kavli Institute for Cosmological Physics, and the University of Chicago. This work was supported by the Kavli Institute for Cosmological Physics at the University of Chicago through NSF Grant Nos. PHY-0114422 and PHY- 0551142, and by the Gordon and Betty Moore Foundation at Caltech.

Additional details

Created:
August 19, 2023
Modified:
October 19, 2023