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I examine how two specific examples of modified gravity explanations of cosmic acceleration help us understand some general problems confronting cosmological tests of gravity: how do we distinguish modified gravity from dark energy if they…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-05 Wayne Hu

In the context of scalar tensor theories for gravity, there is a universally adopted hypothesis when running N-body simulations that time derivatives in the equation of motion for the scalar field are negligible. In this work we propose to…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-04 Claudio Llinares , David F. Mota

We present an upgraded version of \textsc{MG-MAMPOSSt}, an extension of the \textsc{MAMPOSSt} algorithm that performs Bayesian fits of models of mass and velocity anisotropy profiles to the distribution of tracers in projected phase space,…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-13 Lorenzo Pizzuti , Ippocratis D. Saltas , Luca Amendola

It is well-known that allowing for spatial curvature affects constraints on cosmological parameters such as the dark energy equation of state parameters. Here we study the effect of curvature on constraints on parameters used to test…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Jason Dossett , Mustapha Ishak

A modified Mimetic gravity (MMG) is proposed as a generalization of general relativity. The model contain a physical metric which is function of an auxiliary (unphysical) metric and a Lyra's metric. We construct different kinds of…

General Relativity and Quantum Cosmology · Physics 2015-04-07 Davood Momeni , Aziza Altaibayeva , Ratbay Myrzakulov

We present a new massively parallel code for N-body and cosmological hydrodynamical simulations of modified gravity models. The code employs a multigrid-accelerated Newton-Gauss-Seidel relaxation solver on an adaptive mesh to efficiently…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Ewald Puchwein , Marco Baldi , Volker Springel

Numerical simulations are a versatile tool providing insight into the complicated process of structure formation in cosmology. This process is mainly governed by gravity, which is the dominant force on large scales. To date, a century after…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-04 Julian Adamek , David Daverio , Ruth Durrer , Martin Kunz

Modified Growth with {\tt CAMB} ({\tt MGCAMB}) is a patch for the Einstein-Boltzmann solver {\tt CAMB} for cosmological tests of gravity. Until now, {\tt MGCAMB} was limited to scales well-described by linear perturbation theory. In this…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-18 Zhuangfei Wang , Daniela Saadeh , Kazuya Koyama , Levon Pogosian , Benjamin Bose , Lanyang Yi , Gong-Bo Zhao

Future large-scale structure surveys of the Universe will aim to constrain the cosmological model and the true nature of dark energy with unprecedented accuracy. In order for these surveys to achieve their designed goals, they will require…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Robert E. Smith , Darren S. Reed , Doug Potter , Laura Marian , Martin Crocce , Ben Moore

Theories in which gravity is weaker on cosmological scales have been proposed to explain the observed acceleration of the universe. The nonlinear regime in such theories is not well studied, though it is likely that observational tests of…

Astrophysics · Physics 2009-11-11 Hans F. Stabenau , Bhuvnesh Jain

Cosmological $N$-body simulations are typically purely run with particles using Newtonian equations of motion. However, such simulations can be made fully consistent with general relativity using a well-defined prescription. Here, we extend…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-20 Thomas Tram , Jacob Brandbyge , Jeppe Dakin , Steen Hannestad

The new generation of galaxy surveys will provide unprecedented data allowing us to test gravity at cosmological scales. A robust cosmological analysis of the large-scale structure demands exploiting the nonlinear information encoded in the…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-13 Jorge Enrique García-Farieta , Héctor J Hortúa , Francisco-Shu Kitaura

In 'modified' gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-27 Clare Burrage , David Parkinson , David Seery

We present a suite of cosmological N-body simulations describing the "Running Friedmann-Lema{\"i}tre-Robertson-Walker" (R-FLRW) cosmological model. This model is based on quantum field theory in a curved space-time and extends {\Lambda}CDM…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 Antonio Bibiano , Darren J. Croton

We implement an adaptation of the COLA approach, a hybrid scheme that combines Lagrangian perturbation theory with an N-body approach, to model non-linear collapse in chameleon and symmetron modified gravity models. Gravitational screening…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-30 Georgios Valogiannis , Rachel Bean

The subject of this paper is to investigate the weak regime covariant scalar-tensor-vector gravity (STVG) theory, known as the MOdified gravity (MOG) theory of gravity. First, we show that the MOG in the absence of scalar fields is…

General Relativity and Quantum Cosmology · Physics 2018-10-09 M. Khurshudyan , N. S. Mazhari , D. Momeni , R. Myrzakulov , M. Raza

We present a convolutional neural network to classify distinct cosmological scenarios based on the statistically similar weak-lensing maps they generate. Modified gravity (MG) models that include massive neutrinos can mimic the standard…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-17 Austin Peel , Florian Lalande , Jean-Luc Starck , Valeria Pettorino , Julian Merten , Carlo Giocoli , Massimo Meneghetti , Marco Baldi

The observed accelerated expansion of the Universe may be explained by dark energy or the breakdown of general relativity (GR) on cosmological scales. When the latter case, a modified gravity scenario, is considered, it is often assumed…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-04 Jiro Matsumoto , Teppei Okumura , Misao Sasaki

Reliable analytical modeling of the non-linear power spectrum (PS) of matter perturbations is among the chief pre-requisites for cosmological analyses from the largest sky surveys. This is especially true for the models that extend the…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-10 Suhani Gupta , Wojciech A. Hellwing , Maciej Bilicki

We present a numerical code for multi-component simulation of the galactic evolution. Our code includes the following parts: $N$-body is used to evolve dark matter, stellar dynamics and dust grains, gas dynamics is based on TVD-MUSCL scheme…

Computational Physics · Physics 2015-02-11 S. A. Khoperskov , E. O. Vasiliev , A. V. Khoperskov , V. N. Lubimov