Related papers: Chameleon Field in a Spherical Shell System
Following work by Khoury and Weltman, we introduce a scalar field phi, the chameleon, which is conformally coupled to matter. That is, matter experiences a metric which is a conformal transform (parametrized by phi) of the Einstein metric.…
As a result of non-linear self-interactions, in chameleon theories where the field couples to matter much more strongly than gravity does, the fifth force between two bodies with thin-shell is independent of their coupling to the field. As…
We investigate the gas density, temperature, and pressure profiles in a dark matter halo under the influence of the chameleon force. We solve the hydrostatic equilibrium equation for the gas coupled with the chameleon field in an analytic…
We derive analytic solutions of a chameleon scalar field $\phi$ that couples to a non-relativistic matter in the weak gravitational background of a spherically symmetric body, paying particular attention to a field mass $m_A$ inside of the…
Scalar-tensor theories whose phenomenology differs significantly from general relativity on large (e.g. cosmological) scales do not typically pass local experimental tests (e.g. in the solar system) unless they present a suitable "screening…
We extend the chameleon models by considering Scalar-Fluid theories where the coupling between matter and the scalar field can be represented by a quadratic effective potential with density-dependent minimum and mass. In this context, we…
We study constraints on f(R) dark energy models from solar system experiments combined with experiments on the violation of equivalence principle. When the mass of an equivalent scalar field degree of freedom is heavy in a region with high…
Chameleon gravity is an example of a model that gives rise to interesting phenomenology on cosmological scales while simultaneously possessing a screening mechanism, allowing it to avoid solar system constraints. Such models result in…
We consider a hybrid scalar field which is non-minimally coupled to the matter and models a chameleon cosmology. By introducing an effective potential, we study the dependence of the effective potential's minimum and hybrid chameleon…
The chameleon screening mechanism has been constrained many a time using dynamic and kinematic galaxy cluster observables. Current constraints are, however, insensitive to different mass components within galaxy clusters and have been…
The nature of dark energy is one of the most outstanding problems in physical science, and various theories have been proposed. It is therefore essential to directly verify or rule out these theories experimentally. However, despite…
We use two new hydrodynamical simulations of $\Lambda$CDM and $f(R)$ gravity to test the methodology used by Wilcox et al. 2015 (W15) in constraining the effects of a fifth force on the profiles of clusters of galaxies. We construct…
We offer predictions of symmetron modified gravity in the neighborhood of realistic dark matter halos. The predictions for the fifth force are obtained by solving the nonlinear symmetron equation of motion in the spherical NFW…
We investigate the dependence of the Vainshtein screening mechanism on the cosmic web morphology of both dark matter particles and halos as determined by ORIGAMI. Unlike chameleon and symmetron screening, which come into effect in regions…
Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to…
Theories that attempt to explain cosmic acceleration by modifying gravity typically introduces a long-range scalar force that needs to be screened on small scales. One common screening mechanism is the chameleon, where the scalar force is…
Theories of gravity that incorporate new scalar degrees of freedom typically require screening mechanisms to ensure consistency with Solar System tests. One widely-studied mechanism -- the chameleon -- can lead to violations of the…
In this paper we investigate gravitationally bound, spherically symmetric equilibrium configurations consisting of ordinary (polytropic) matter nonminimally coupled to an external chameleon scalar field. We show that this system has static,…
By studying the chameleon gravity on galaxy scales, we investigate the effects of the chameleon dark matter. To perform this task, we consider the dynamics of the chameleon scalar field in the region of galactic halos in static spherically…
We compute bounds from atomic spectroscopy on chameleon fields that couple to the photon. Chameleons are a wide class of scalar field models that generically lead to screened fifth forces and a host of novel phenomenologies, particularly…