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The statistics of dark matter halos is an essential component of understanding the nonlinear evolution in modified gravity cosmology. Based on a series of modified gravity N-body simulations, we investigate the halo mass function,…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-21 Youcai Zhang , Pengjie Zhang , Xiaohu Yang , Weiguang Cui

The analysis of perturbative quantities is a powerful tool to distinguish between different Dark Energy models and gravity theories degenerated at the background level. In this work, we generalise the integral solution of the matter density…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-06 J. E. Gonzalez

A type of exponential correction to General Relativity gives viable modified gravity model of dark energy. The model behaves as $R-2\Lambda$ at large curvature where an effective cosmological constant appears, but it becomes zero in flat…

General Relativity and Quantum Cosmology · Physics 2022-01-13 L. N. Granda

Dynamical mass discrepancies in galaxies have two possible explanations: the existence of large amounts of dark matter or the breakdown of Newtonian gravity. True dark matter halos of galaxies could differ in several respects from apparent…

Astrophysics · Physics 2007-05-23 J. A. Sellwood , A. Kosowsky

We develop the general scheme for modified $f(R)$ gravity reconstruction from any realistic FRW cosmology. We formulate several versions of modified gravity compatible with Solar System tests where the following sequence of cosmological…

High Energy Physics - Theory · Physics 2008-11-26 Shin'ichi Nojiri , Sergei D. Odintsov

We develop a parameterized post-Friedmann (PPF) framework which describes three regimes of modified gravity models that accelerate the expansion without dark energy. On large scales, the evolution of scalar metric and density perturbations…

Astrophysics · Physics 2008-11-26 Wayne Hu , Ignacy Sawicki

Accurate predictions for the non-linear matter power spectrum are needed to confront theory with observations in current and near future weak lensing and galaxy clustering surveys. We propose a computationally cheap method to create an…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-01 Hans Winther , Santiago Casas , Marco Baldi , Kazuya Koyama , Baojiu Li , Lucas Lombriser , Gong-Bo Zhao

We consider spatially covariant modified gravity in which the would-be scalar degree of freedom is made non-dynamical and hence there are just two tensorial degrees of freedom, i.e., the same number of dynamical degrees of freedom as in…

General Relativity and Quantum Cosmology · Physics 2021-12-15 Aya Iyonaga , Tsutomu Kobayashi

We study the effect of modified gravity on weak lensing in a class of scalar-tensor theory that includes $f(R)$ gravity as a special case. These models are designed to satisfy local gravity constraints by having a large scalar-field mass in…

Astrophysics · Physics 2009-06-23 Shinji Tsujikawa , Takayuki Tatekawa

Modifications of General Relativity generically contain additional degrees of freedom that can mediate forces between matter particles. One of the common manifestations of a fifth force in alternative gravity theories is a difference…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-22 Camille Bonvin , Levon Pogosian

Extremely large surveys with future experiments like Euclid and the SKA will soon allow us to access perturbation modes close to the Hubble scale, with wavenumbers $k \sim \mathcal{H}$. If a modified gravity theory is responsible for cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2015-11-03 Tessa Baker , Philip Bull

We consider the impact of key astrophysical and measurement systematics on constraints on dark energy and modifications to gravity on cosmic scales. We focus on upcoming photometric "Stage III" and "Stage IV" large scale structure surveys…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Istvan Laszlo , Rachel Bean , Donnacha Kirk , Sarah Bridle

We describe how a certain simple modification of general relativity, in which the local cosmological constant is allowed to depend on the space-time curvature, predicts the existence of halos of modified gravity surrounding…

General Relativity and Quantum Cosmology · Physics 2009-03-20 Kirill Krasnov , Yuri Shtanov

Modified dark matter (MDM, formerly known as MoNDian dark matter) is a phenomenological model of dark matter, inspired by quantum gravity. We review the construction of MDM by generalizing entropic gravity to de-Sitter space as is…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-02 Y. Jack Ng , Doug Edmonds , Duncan Farrah , Djordje Minic , Tatsu Takeuchi , Chiu Man Ho

Weak lensing (WL) promises to be a particularly sensitive probe of both the growth of large scale structure (LSS) as well as the fundamental relation between matter density perturbations and metric perturbations, thus providing a powerful…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 Geraint Pratten , Dipak Munshi , Patrick Valageas , Philippe Brax

We forecast constraints on minimal model-independent parametrisations of several Modified Gravity theories using mock Stage-IV cosmic shear data. We include nonlinear effects and screening, which ensures recovery of General Relativity on…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-18 Maria Tsedrik , Benjamin Bose , Pedro Carrilho , Alkistis Pourtsidou , Sefa Pamuk , Santiago Casas , Julien Lesgourgues

The observed acceleration of the universe, explained through dark energy, could alternatively be explained through a modification of gravity that would also induce modifications in the evolution of cosmological perturbations. We use new…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-16 Ismael Tereno , Elisabetta Semboloni , Tim Schrabback

We examine general physical parameterisations for viable gravitational models in the $f(R)$ framework. This is related to the mass of an additional scalar field, called the scalaron, that is introduced by the theories. Using a simple…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Shaun A. Thomas , Stephen A. Appleby , Jochen Weller

We present the first suite of cosmological N-body simulations that simultaneously include the effects of two different and theoretically independent extensions of the standard $\Lambda$CDM cosmological scenario - namely an $f(R)$ theory of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Marco Baldi , Francisco Villaescusa-Navarro , Matteo Viel , Ewald Puchwein , Volker Springel , Lauro Moscardini

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