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We investigate chaos in the dynamics of massless particles near the horizon of static spherically symmetric black holes in two well-motivated models of $f(R)$ gravity. In both these models, we probe chaos in the particle trajectories (under…

General Relativity and Quantum Cosmology · Physics 2024-12-17 Surajit Das , Surojit Dalui , Rickmoy Samanta

In this paper we investigate dark matter structure formation in the normal branch of the Dvali-Gabadadze-Porrati (nDGP) model using the PINOCCHIO algorithm. We first present 2nd order Lagrangian perturbation theory for the nDGP model, which…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-27 Yanling Song , Bin Hu , Chengzong Ruan , Chiara Moretti , Pierluigi Monaco

In this study, we investigate gravitational lensing within modified gravity frameworks, focusing on the Hu-Sawicki $f(R)$ and normal branch Dvali-Gabadadze-Porrati (nDGP) models, and we compare these results with those obtained from general…

General Relativity and Quantum Cosmology · Physics 2025-01-03 Ali Tizfahm , Saeed Fakhry , Javad T. Firouzjaee , Antonino Del Popolo

Fuzzy dark matter (FDM) is an attractive dark matter candidate composed of ultralight particles. In this paper, toward a clear understanding of the core-halo relation in the FDM halos, we consider a simple model of the soliton-halo system,…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-25 Yusuke Manita , Takuya Takahashi , Atsushi Taruya

If modified gravity holds, but the weak lensing analysis is done in the standard way, one finds that dark matter halos have peculiar shapes, not following the standard Navarro-Frenk-White profiles, and are fully predictable from the…

Astrophysics of Galaxies · Physics 2026-02-20 Michal Bílek

We consider the effect of modified gravity on the growth of large-scale structures at second order in perturbation theory. We show that modified gravity models changing the linear growth rate of fluctuations are also bound to change,…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 Francis Bernardeau , Philippe Brax

We present two new diagnostics based on the intrinsic shape alignments of group/cluster size dark matter halos to disentangle the effect of $f(R)$ gravity from that of massive neutrinos. Using the snapshot data from a series of the {\small…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-09 Jounghun Lee , Suho Ryu , Marco Baldi

We present the nonlinear growth of bound cosmological structures using the spherical collapse approach in the shift-symmetric Galileon theories. In particular, we focus on the class of models belonging to the Kinetic Gravity Braiding by…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-09 Inês S. Albuquerque , Noemi Frusciante , Francesco Pace , Carlo Schimd

Explanations to the accelerated expansion of the Universe are usually sought either in modifications of Einstein gravity or in new forms of energy density. An example of modified gravity is the braneworld Dvali-Gabadadze-Porrati (DGP) model…

Astrophysics · Physics 2008-04-22 Matts Roos

Cosmologists today are confronted with the perplexing reality that the universe is currently accelerating in its expansion. Nevertheless, the nature of the fuel that drives today's cosmic acceleration is an open and tantalizing mystery.…

Astrophysics · Physics 2008-11-26 Arthur Lue

We study a theory of gravity in which the action is a result from the general purely disformal transformation on the Einstein-Hilbert action. This theory is a sub-class of GLPV theory which is the the generalization of covariant Galileon.…

General Relativity and Quantum Cosmology · Physics 2017-06-13 Khamphee Karwan , David F. Mota , Saksith Jaksri

We introduce a cosmological model based on the normal branch of DGP braneworld gravity with a smooth dark energy component on the brane. The expansion history in this model is identical to LambdaCDM, thus evading all geometric constraints…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-02 Fabian Schmidt

Theories of modified gravity attempt to reconcile physics at the largest and the smallest scales by explaining the accelerated expansion of our universe without introducing the cosmological constant. One class of such theories, known as…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-11 Youngsoo Park , Mark Wyman

Future large-scale structure surveys will measure three-point statistics with high statistical significance. This will offer significant improvements on our understanding of gravity, provided we can model these statistics accurately. We…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-04 Benjamin Bose , Joyce Byun , Fabien Lacasa , Azadeh Moradinezhad Dizgah , Lucas Lombriser

We examine the nonlinear structure of gravitationally collapsed objects that form in our simulations of wavelike cold dark matter ($\psi$DM), described by the Schr\"{o}dinger-Poisson (SP) equation with a particle mass $\sim 10^{-22} {\rm…

We investigate static spherically symmetric solutions of nonlinear massive gravities. We first identify, in an ansatz appropriate to the study of those solutions, the analog of the decoupling limit (DL) that has been used in the Goldstone…

High Energy Physics - Theory · Physics 2009-05-29 E. Babichev , C. Deffayet , R. Ziour

We consider the consequences of the absence of Birkhoff's theorem in theories of modified gravity. As an example, we calculate the gravitational force on a test particle due to a spherical mass shell in the Dvali-Gabadaze-Porrati model…

General Relativity and Quantum Cosmology · Physics 2008-11-26 De-Chang Dai , Irit Maor , Glenn Starkman

Adaptive SPH and N-body simulations were carried out to study the effect of gasdynamics on the structure of dark matter halos that result from the gravitational instability and fragmentation of cosmological pancakes. Such halos resemble…

Astrophysics · Physics 2007-05-23 Marcelo Alvarez , Paul R. Shapiro , Hugo Martel

Adaptive SPH and N-body simulations were carried out to study the evolution of the equilibrium structure of dark matter halos that result from the gravitational instability and fragmentation of cosmological pancakes. Such halos resemble…

Astrophysics · Physics 2009-11-06 Marcelo Alvarez , Paul R. Shapiro , Hugo Martel