Related papers: Dark halos built of scalar gravitons: numerical st…
We consider the possibility that the dark matter is coupled through its mass to a scalar field associated with the dark energy of the Universe. In order for such a field to play a role at the present cosmological distances, it must be…
This paper is a sequel to the author's paper entitled "On Dark Matter, Spiral Galaxies, and the Axioms of General Relativity" [arXiv:1004.4016] which explored a geometrically natural axiomatic definition for dark matter modeled by a scalar…
According to a scalar theory of gravity with a preferred frame, electromagnetism in the presence of a gravitational field implies that there is an additional energy tensor, which might contribute to dark matter. The expression of this…
We explore a novel cosmological model based on coupled fields in the framework of scalar tensor theories, considering the specific interplay between gravity and scalar fields. The model further extends a recent axion-dilaton system by…
The lack of detection of supersymmetric particles is leading to look at alternative avenues for explaining dark matter's effects. Among them, modified theories of gravity may play an important role accounting even for both dark components…
Although the standard cosmological model, the so-called $\Lambda$ Cold Dark Matter ("$\Lambda$CDM"), appears to fit well observations at the cosmological level, it is well known that it possesses several inconsistencies at the galactic…
Galactic dark matter is modelled by a scalar field. In particular, it is shown that an analytically solvable toy model with a non-linear self-interaction potential U(Phi) leads to dark halo models which have the form of quasi-isothermal…
Scalar-tensor theories of gravity generally violate the strong equivalence principle, namely compact objects have a suppressed coupling to the scalar force, causing them to fall slower. A black hole is the extreme example where such a…
We explore a new horizon of modified gravity from the viewpoint of the particle physics. As a concrete example, we take the $F(R)$ gravity to raise a question: can a scalar particle ("scalaron") derived from the $F(R)$ gravity be a dark…
We consider singularities of static spherically symmetric objects in minimal dilatonic gravity. They are only partially studied and purely understood even in the simplest models of extended gravity. We introduce the proper form of the…
We investigate the possibility that the observed behavior of test particles outside galaxies, which is usually explained by assuming the existence of dark matter, is the result of the dynamical evolution of particles in a Weyl type…
The Hamiltonian formalism of the generalized unimodular gravity theory, which was recently suggested as a model of dark energy, is shown to be a complicated example of constrained dynamical system. The set of its canonical constraints has a…
The main purpose of this paper is to advance a unified theory of dark matter, dark energy, and inflation first formulated in 2008. Our minimal affine extension of the GR has geodesics coinciding with the pseudo Riemannian ones, up to…
In $f(R)$ gravity, the scalaron -- a scalar degree of freedom arising from modification of General Relativity -- could account for all dark matter in the universe if its mass lies in the meV--MeV range. In this work, we revisit the…
The observed excess of gravitational forces in galaxies and galactic clusters is usually referred as the existence of "dark matter particles" of unknown origin. An alternative explanation of the dark matter effect is presented here by…
We review the formalism and applications of the halo-based description of nonlinear gravitational clustering. In this approach, all mass is associated with virialized dark matter halos; models of the number and spatial distribution of the…
The nature of the dark matter that binds galaxies remains an open question. The favored candidate has been so far the neutralino. This massive species with evanescent interactions is now in difficulty. It would actually collapse in dense…
We study dynamics of generalized tachyon scalar field in the framework of teleparallel gravity. This model is an extension of tachyonic teleparallel dark energy model which has been proposed in [26]. In contrast with tachyonic teleparallel…
The stable pseudo-scalar degree of freedom of the quadratic Poincar\'e Gauge theory of gravity is shown to be a suitable dark matter candidate. We find the parameter space of the theory which can account for all the predicted cold dark…
Classical scalar fields have been proposed as possible candidates for the dark matter component of the universe. Given the fact that super-massive black holes seem to exist at the center of most galaxies, in order to be a viable candidate…