Spherical Collapse in ƒ(R) Gravity

We use one-dimensional numerical simulations to study spherical collapse in the ƒ(R) gravity models. We include the nonlinear self-coupling of the scalar field in the theory and use a relaxation scheme to follow the collapse. We find an unusual enhancement in density near the virial radius which may provide observable tests of gravity. We also use the estimated collapse time to calculate the critical overdensity δc used in calculating the mass function and bias of halos. We find that analytical approximations previously used in the literature do not capture the complexity of nonlinear spherical collapse. Disciplines Physical Sciences and Mathematics | Physics Comments Borisov, A., Jain, B., & Zhang, P. (2012). Spherical Collapse in ƒ(R) Gravity. Physical Review D, 85(6), 063518. doi: 10.1103/PhysRevD.85.063518 © 2012 American Physical Society This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/230 Spherical collapse in fðRÞ gravity Alexander Borisov, Bhuvnesh Jain, and Pengjie Zhang* Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Nandan Road 80, Shanghai, 200030, China (Received 13 March 2011; published 23 March 2012) We use one-dimensional numerical simulations to study spherical collapse in the fðRÞ gravity models. We include the nonlinear self-coupling of the scalar field in the theory and use a relaxation scheme to follow the collapse. We find an unusual enhancement in density near the virial radius which may provide observable tests of gravity. We also use the estimated collapse time to calculate the critical overdensity c used in calculating the mass function and bias of halos. We find that analytical approximations previously used in the literature do not capture the complexity of nonlinear spherical collapse. DOI: 10.1103/PhysRevD.85.063518 PACS numbers: 98.65.Dx, 04.50. h, 95.36.+x