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In the context of modified gravity, at linear level, the growth of structure in the Universe will be affected by modifications to the Poisson equation and by the background expansion rate of the Universe. It has been shown that these two…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-08 Jaime Ruiz-Zapatero , David Alonso , Pedro G. Ferreira , Carlos Garcia-Garcia

A probability of distinguishing between $\Lambda$CDM model and modified gravity is studied by using the future observations for the growth rate of cosmic structure (Euclid redshift survey). Adopting extended DGP model, Kinetic Gravity…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-31 Koichi Hirano

We explore the generalized $f(R,T)$ modified theory of gravity, where the gravitational Lagrangian is a function of Ricci scalar $R$ and the trace of the energy-momentum tensor $T$. We derive modified field equations to the linear order of…

General Relativity and Quantum Cosmology · Physics 2024-10-29 Mahnaz Asghari , Ahmad Sheykhi

We investigate the evolution of cosmic structures within the framework of modified gravity, specifically focusing on theories described by the function $f(R, L_m)$, where $R$ is the Ricci scalar and $L_m$ is the matter Lagrangian. This…

General Relativity and Quantum Cosmology · Physics 2025-07-08 G. K. Goswami , J. P. Saini

Disformal theories of gravity are scalar-tensor theories where the scalar couples derivatively to matter via the Jordan frame metric. These models have recently attracted interest in the cosmological context since they admit accelerating…

General Relativity and Quantum Cosmology · Physics 2015-11-04 Hiu Yan Ip , Jeremy Sakstein , Fabian Schmidt

In this review we present a thoroughly comprehensive survey of recent work on modified theories of gravity and their cosmological consequences. Amongst other things, we cover General Relativity, Scalar-Tensor, Einstein-Aether, and Bimetric…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Timothy Clifton , Pedro G. Ferreira , Antonio Padilla , Constantinos Skordis

We study the evolution of linear perturbations in metric f(R) models of gravity and identify a potentially observable characteristic scale-dependent pattern in the behavior of cosmological structures. While at the background level viable…

Astrophysics · Physics 2014-11-18 Levon Pogosian , Alessandra Silvestri

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 a gravitational model in which scale transformations play the key role in obtaining dynamical $G$ and $\Lambda$. We take a scale non-invariant gravitational action with a cosmological constant and a gravitational coupling constant.…

General Relativity and Quantum Cosmology · Physics 2015-05-13 F. Darabi

We compare a large suite of theoretical cosmological models to observational data from the cosmic microwave background, baryon acoustic oscillation measurements of expansion, Type Ia SNe measurements of expansion, redshift space distortion…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-13 Zhongxu Zhai , Michael Blanton , Anže Slosar , Jeremy Tinker

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

We examine the growth of structure in three different cosmological models with interacting dark matter and vacuum energy. We consider the case of geodesic dark matter with zero sound speed, where the relativistic growing mode in…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-20 Humberto A Borges , David Wands

We present a case that current observations may already indicate new gravitational physics on cosmological scales. The excess of power seen in the Lyman-alpha forest and small-scale CMB experiments, the anomalously large bulk flows seen…

Astrophysics · Physics 2010-04-23 Niayesh Afshordi , Ghazal Geshnizjani , Justin Khoury

We model the chameleon effect on cosmological statistics for the modified gravity f(R) model of cosmic acceleration. The chameleon effect, required to make the model compatible with local tests of gravity, reduces force enhancement as a…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-07 Yin Li , Wayne Hu

The modified gravity with $\ln R$ or $R^{-n} (\ln R)^m$ terms which grow at small curvature is discussed. It is shown that such a model which has well-defined newtonian limit may eliminate the need for dark energy and may provide the…

High Energy Physics - Theory · Physics 2009-09-17 Shin'ichi Nojiri , Sergei D. Odintsov

In this paper we investigate the cosmological effects of modified gravity with string curvature corrections added to Einstein-Hilbert action in the presence of a dynamically evolving scalar field coupled to Riemann invariants. The scenario…

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

It has been argued that the small perturbations to the homogeneous and isotropic configurations of a canonical scalar field in an expanding universe do not grow. We show that this is not true in general, and clarify the root of the…

General Relativity and Quantum Cosmology · Physics 2015-09-23 Miguel Alcubierre , Axel de la Macorra , Alberto Diez-Tejedor , José M. Torres

We consider quintessence scalar field cosmology in which the Lagrangian of the scalar field is modified by the Generalized Uncertainty Principle. We show that the perturbation terms which arise from the deformed algebra are equivalent with…

General Relativity and Quantum Cosmology · Physics 2015-12-03 Andronikos Paliathanasis , Supriya Pan , Souvik Pramanik

In models of modified gravity, extra degrees of freedom usually appear. They must be removed from the spectrum because they may indicate the presence of instabilities and because otherwise the model might not agree with observation. In the…

High Energy Physics - Theory · Physics 2014-11-18 Luca Grisa

Modified gravity theories have richer observational consequences for large-scale structure than conventional dark energy models, in that different observables are not described by a single growth factor even in the linear regime. We examine…

Astrophysics · Physics 2009-02-20 Bhuvnesh Jain , Pengjie Zhang
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