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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

This paper is a review of the relationship between the metric formulation of (2+1)-dimensional gravity and the loop observables of Rovelli and Smolin. I emphasize the possibility of reconstructing the geometry, via the theory of geometric…

General Relativity and Quantum Cosmology · Physics 2007-05-23 S. Carlip

We present release 2.0 of the ALPS (Algorithms and Libraries for Physics Simulations) project, an open source software project to develop libraries and application programs for the simulation of strongly correlated quantum lattice models…

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

It has been recently proposed that gravity might be an entropic force. Although a well defined fundamental description for such a mechanism is still lacking, it is still possible to address the viability of phenomenological models of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Miguel Zumalacarregui

In this review we briefly summarize the so-called effective fluid approach, which is a compact framework that can be used to describe a plethora of different modified gravity models as general relativity (GR) and a dark energy (DE) fluid.…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-03 Savvas Nesseris

We describe the special relativistic extension of the CRONOS code, which has been used for studies of gamma-ray binaries in recent years. The code was designed to be easily adaptable, allowing the user to easily change existing…

High Energy Astrophysical Phenomena · Physics 2021-09-29 David Huber , Ralf Kissmann

We consider modified gravity cosmological models that can be transformed into two-field chiral cosmological models by the conformal metric transformation. For the $R^2$ gravity model with an additional scalar field and the corresponding…

General Relativity and Quantum Cosmology · Physics 2021-11-11 Vsevolod R. Ivanov , Sergey Yu. Vernov

The landscape of high- and ultra-high-energy astrophysics has changed in the last decade, largely due to the inflow of data collected by large-scale cosmic-ray, gamma-ray, and neutrino observatories. At the dawn of the multimessenger era,…

In this paper, exact wormhole solutions in the context of $f(R)$ theory of gravity are investigated. Since the Einstein field equations are modified in 3+1 dimensions in the $f(R)$ theory of gravity, we have studied some possible solutions…

General Relativity and Quantum Cosmology · Physics 2021-10-15 Foad Parsaei , Sara Rastgoo

The precise tuning required to observe critical phenomena in gravitational collapse poses a challenge for most numerical codes. First, threshold estimation searches may be obstructed by the appearance of coordinate singularities, indicating…

General Relativity and Quantum Cosmology · Physics 2024-09-24 Daniela Cors , Sarah Renkhoff , Hannes R. Rüter , David Hilditch , Bernd Brügmann

We review recent progress of modified gravity models of dark energy--based on f(R) gravity, scalar-tensor theories, braneworld gravity, Galileon gravity, and other theories. In f(R) gravity and Brans-Dicke theory it is possible to design…

General Relativity and Quantum Cosmology · Physics 2011-02-01 Shinji Tsujikawa

We present MG-GLAM, a code developed for the very fast production of full $N$-body cosmological simulations in modified gravity (MG) models. We describe the implementation, numerical tests and first results of a large suite of cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-13 Cheng-Zong Ruan , César Hernández-Aguayo , Baojiu Li , Christian Arnold , Carlton M. Baugh , Anatoly Klypin , Francisco Prada

This paper is the third in a series on tests of gravity using observations of stars and nearby dwarf galaxies. We carry out four distinct tests using published data on the kinematics and morphology of dwarf galaxies, motivated by the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Vinu Vikram , Anna Cabre , Bhuvnesh Jain , Jake VanderPlas

We present the GLoBES (``General Long Baseline Experiment Simulator'') software package, which allows the simulation of long-baseline and reactor neutrino oscillation experiments. One part of the software is the abstract experiment…

High Energy Physics - Phenomenology · Physics 2016-09-06 P. Huber , M. Lindner , W. Winter

A unified framework for theories of modified gravity will be an essential tool for interpreting the forthcoming deluge of cosmological data. We present such a formalism, the Parameterized Post-Friedmann framework (PPF), which parameterizes…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-08 Tessa Baker , Pedro G. Ferreira , Constantinos Skordis

Modified gravity (MOG) is a covariant, relativistic, alternative gravitational theory whose field equations are derived from an action that supplements the spacetime metric tensor with vector and scalar fields. Both gravitational (spin 2)…

General Relativity and Quantum Cosmology · Physics 2018-03-14 M. A. Green , J. W. Moffat , V. T. Toth

We present GRAMSES, a new pipeline for nonlinear cosmological $N$-body simulations in General Relativity (GR). This code adopts the Arnowitt-Deser-Misner (ADM) formalism of GR, with constant mean curvature and minimum distortion gauge…

Cosmology and Nongalactic Astrophysics · Physics 2020-03-24 Cristian Barrera-Hinojosa , Baojiu Li

Modified theories of gravity have been invoked recently as an alternative to dark energy, in an attempt to explain the apparent accelerated expansion of the universe at the present time. In order to describe inhomogeneities in cosmological…

General Relativity and Quantum Cosmology · Physics 2016-04-15 Adam J. Christopherson

The gauge polyvalence of a new numerical code is tested, both in harmonic-coordinate simulations (gauge-waves testbed) and in singularity-avoiding coordinates (simple Black-Hole simulations, either with or without shift). The code is built…

General Relativity and Quantum Cosmology · Physics 2009-09-02 Daniela Alic , Carles Bona , Carles Bona-Casas