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We consider the effect of modified gravity on the peak structure of the Cosmic Microwave Background (CMB) spectrum. We focus on simple models of modified gravity mediated by a massive scalar field coupled to both baryons and cold dark…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Philippe Brax , Anne-Christine Davis

Scalar modifications of gravity have an impact on the growth of structure. Baryon and Cold Dark Matter (CDM) perturbations grow anomalously for scales within the Compton wavelength of the scalar field. In the late time Universe when…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Philippe Brax , Sébastien Clesse , Anne-Christine Davis

One way to account for the acceleration of the universe is to modify general relativity, rather than introducing dark energy. Typically, such modifications introduce new degrees of freedom. It is interesting to consider models with no new…

Astrophysics · Physics 2011-05-12 Sean M. Carroll , Ignacy Sawicki , Alessandra Silvestri , Mark Trodden

We consider modified gravity models driven by a scalar field whose effects are screened in high density regions due to the presence of non-linearities in its interaction potential and/or its coupling to matter. Our approach covers…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Philippe Brax , Anne-Christine Davis , Baojiu Li , Hans A. Winther

We study the linear and nonlinear structure formation in the dilaton and symmetron models of modified gravity using a generic parameterisation which describes a large class of scenarios using only a few parameters, such as the coupling…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Philippe Brax , Anne-Christine Davis , Baojiu Li , Hans A. Winther , Gong-Bo Zhao

We study the growth of structures in modified gravity models where the Poisson equation and the relationship between the two Newtonian potentials are modified by explicit functions of space and time. This parameterisation applies to the…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-24 Philippe Brax , Patrick Valageas

Cosmic growth of large scale structure probes the entire history of cosmic expansion and gravitational coupling. To get a clear picture of the effects of modification of gravity we consider a deviation in the coupling strength (effective…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-19 Mikhail Denissenya , Eric V. Linder

We consider the effect of a scalar field degree of freedom on the dynamics of gravity from small to large scales. We show that the effects of modified gravity can be completely captured by the time variations of the scalar field mass and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Philippe Brax , Anne-Christine Davis , Baojiu Li

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

In this work we study the simultaneous effect of primordial non-Gaussianity and the modification of the gravity in $f(R)$ framework on large scale structure observations. We show that non-Gaussianity and modified gravity introduce a scale…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-12 Nareg Mirzatuny , Shahram Khosravi , Shant Baghram , Hossein Moshafi

The review is devoted to consideration of possible observational consequences of modified gravity theories, suggested for explanation of the contemporary accelerated expansion of the universe. The major attention is paid to F(R)-models. It…

General Relativity and Quantum Cosmology · Physics 2019-11-11 Elena Arbuzova

The acceleration of the expansion of the Universe has led to the construction of Dark Energy models where a light scalar field may have a range reaching up to cosmological scales. Screening mechanisms allow these models to evade the tight…

High Energy Physics - Theory · Physics 2012-11-26 Philippe Brax

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

We suggest a new efficient way to constrain a certain class of large scale modifications of gravity. We show that the scale-free relation between density and size of Dark Matter halos, predicted within the LambdaCDM model with Newtonian…

High Energy Physics - Theory · Physics 2011-01-04 Alexey Boyarsky , Oleg Ruchayskiy

We present a formalism to compute Lagrangian displacement fields for a wide range of cosmologies in the context of perturbation theory up to third order. We emphasize the case of theories with scale dependent gravitational strengths, such…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-16 Alejandro Aviles , Jorge L. Cervantes-Cota

We consider a DGP brane scenario where a scalar field is present on the brane through the introduction of a scalar potential, itself motivated by the notion of modified gravity. This theory predicts that the mass appearing in the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 K. Atazadeh , H. R. Sepangi

A scalar-tensor theory of gravity can be made not only to account for the current cosmic acceleration, but also to satisfy solar-system and laboratory constraints, by introducing a non-linear derivative interaction for the scalar field.…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 Tsutomu Kobayashi , Hiroyuki Tashiro , Daichi Suzuki

Chameleon fields may modify gravity on cluster scales while recovering general relativity locally. This article reviews signatures of chameleon modifications in the nonlinear cosmological structure, comparing different techniques to model…

Cosmology and Nongalactic Astrophysics · Physics 2015-01-06 Lucas Lombriser

We carry out a suite of cosmological simulations of modified action f(R) models where cosmic acceleration arises from an alteration of gravity instead of dark energy. These models introduce an extra scalar degree of freedom which enhances…

Astrophysics · Physics 2008-12-30 Hiroaki Oyaizu , Marcos Lima , Wayne Hu

We study the effects of modifications of gravity after Big Bang Nucleosynthesis (BBN) which would manifest themselves mainly before recombination. We consider their effects on the Cosmic Microwave Background (CMB) radiation and on the…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-18 Philippe Brax , Carsten van de Bruck , Sebastien Clesse , Anne-Christine Davis , Gregory Sculthorpe
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