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We describe a major update to the public GIZMO code. GIZMO has been used in simulations of cosmology; galaxy and star formation and evolution; black hole accretion and feedback; proto-stellar disk dynamics and planet formation; fluid…

Instrumentation and Methods for Astrophysics · Physics 2017-12-06 Philip F. Hopkins

GYOTO, a general relativistic ray-tracing code, is presented. It aims at computing images of astronomical bodies in the vicinity of compact objects, as well as trajectories of massive bodies in relativistic environments. This code is…

General Relativity and Quantum Cosmology · Physics 2012-03-15 Frederic H. Vincent , Thibaut Paumard , Eric Gourgoulhon , Guy Perrin

We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied $f(R)$ gravity models. High resolution simulations for such models are…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-14 Sownak Bose , Baojiu Li , Alexandre Barreira , Jian-hua He , Wojciech A. Hellwing , Kazuya Koyama , Claudio Llinares , Gong-Bo Zhao

We compare the results of two--dimensional simulations to experimental data obtained at Los Alamos National Laboratory in order to validate the FLASH code. FLASH is a multi--physics, block--structured adaptive mesh refinement code for…

Astrophysics · Physics 2007-05-23 Vikram Dwarkadas , Tomek Plewa , Greg Weirs , Chris Tomkins , Mark Marr-Lyon

This paper is a collection of lecture notes on modified gravity. Various modified gravity models formulated within the Riemannian formalism are discussed.

General Relativity and Quantum Cosmology · Physics 2020-08-03 A. Yu. Petrov

Numerical simulations in modified gravity have commonly been performed under the quasi-static approximation -- that is, by neglecting the effect of time derivatives in the equation of motion of the scalar field that governs the fifth force…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-26 Sownak Bose , Wojciech A. Hellwing , Baojiu Li

I present the publicly available code GLADIS (GLobal Accretion Disk Instability Simulation) developed in my reserach group over the years 2002-2017. It can be freely downloaded and modified by the users via the link from the Astrophysics…

High Energy Astrophysical Phenomena · Physics 2019-11-14 Agnieszka Janiuk

We consider modified gravity which may describe the early-time inflation and/or late-time cosmic acceleration of the universe. In particular, we discuss the properties of $F(R)$, $F(G)$, string-inspired and scalar-Einstein-Gauss-Bonnet…

General Relativity and Quantum Cosmology · Physics 2013-06-20 Shin'Ichi Nojiri , Sergei D. Odintsov

One of the so-called viable modified gravities is analyzed. This kind of gravity theories are characterized by a well behavior at local scales, where General Relativity is recovered, while the modified terms become important at the…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Diego Sáez-Gómez

Inversions of airborne EM data are often an iterative process, not only requiring that the researcher be able to explore the impact of changing components such as the choice of regularization functional or model parameterization, but also…

Geophysics · Physics 2022-03-29 Lindsey J. Heagy , Seogi Kang , Rowan Cockett , Douglas Oldenburg

We systematically review some standard issues and also the latest developments of modified gravity in cosmology, emphasizing on inflation, bouncing cosmology and late-time acceleration era. Particularly, we present the formalism of standard…

General Relativity and Quantum Cosmology · Physics 2021-05-25 S. Nojiri , S. D. Odintsov , V. K. Oikonomou

In this work, we introduce GRChombo: a new numerical relativity code which incorporates full adaptive mesh refinement (AMR) using block structured Berger-Rigoutsos grid generation. The code supports non-trivial "many-boxes-in-many-boxes"…

General Relativity and Quantum Cosmology · Physics 2016-02-09 Katy Clough , Pau Figueras , Hal Finkel , Markus Kunesch , Eugene A. Lim , Saran Tunyasuvunakool

This review explores modified theories of gravity, particularly $f(R)$ gravity, as extensions to General Relativity (GR) that offer alternatives to dark energy for explaining cosmic acceleration. These models generalize the Einstein-Hilbert…

General Relativity and Quantum Cosmology · Physics 2025-03-05 Rafid H. Dejrah

In this work we systematically study the linear and nonlinear structure formation in chameleon theories of modified gravity, using a generic parameterisation which describes a large class of models using only 4 parameters. For this we have…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-24 Philippe Brax , Anne-C. Davis , Baojiu Li , Hans A. Winther , Gong-Bo Zhao

During hundred years of General Relativity (GR), many significant gravitational phenomena have been predicted and discovered. General Relativity is still the best theory of gravity. Nevertheless, some (quantum) theoretical and…

High Energy Physics - Theory · Physics 2017-01-10 Ivan Dimitrijevic , Branko Dragovich , Jelena Stankovic , Alexey S. Koshelev , Zoran Rakic

Modified gravitational forces in models that seek to explain cosmic acceleration without dark energy typically predict deviations in the abundance of massive dark matter halos. We conduct the first, simulation calibrated, cluster abundance…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-06 Fabian Schmidt , Alexey Vikhlinin , Wayne Hu

This MSc thesis is divided in to two parts. The first, covers the foundations of theories of gravitation, and, the second incorporates original work on the subject of the existence of traversable wormholes in $f(R)$ modified theories of…

General Relativity and Quantum Cosmology · Physics 2011-07-15 Miguel A. Oliveira

Extended Theories of Gravity are considered as a new approach for solving the infrared and ultraviolet scale problems of the Standard Theory of Gravity (General Relativity). Observational evidence of gravitational waves and subsequent…

General Relativity and Quantum Cosmology · Physics 2022-02-16 Sourav Roy Chowdhury , Maxim Khlopov

Modified theories of gravity provide us with a unique opportunity to generate innovative tests of gravity. In Chameleon f(R) gravity, the gravitational potential differs from the weak-field limit of general relativity (GR) in a mass…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-26 Alejo Stark , Christopher J. Miller , Nicholas Kern , Daniel Gifford , Gong-Bo Zhao , Baojiu Li , Kazuya Koyama , Robert C. Nichol

Calculations of the gravitational self-force (GSF) in curved spacetime require as input the metric perturbation in a sufficiently regular gauge. A basic challenge in the program to compute the GSF for orbits around a Kerr black hole is that…

General Relativity and Quantum Cosmology · Physics 2014-01-21 Adam Pound , Cesar Merlin , Leor Barack