Related papers: Spherically symmetric problem on the brane and gal…
The anomalous rotation curves of galaxies provide compelling evidence for dark matter, yet its fundamental nature and distribution remain key unresolved issues in astrophysics. In this work, we investigate a dark matter model derived from…
We present a detailed study of the collapse of a spherical perturbation in DGP braneworld gravity for the purpose of modeling simulation results for the halo mass function, bias and matter power spectrum. The presence of evolving…
Vacuum spherically symmetric loop quantum gravity in the midi-superspace approximation using inhomogeneous horizon-penetrating slices has been studied for a decade, and it has been noted that the singularity is eliminated. It is replaced by…
As an alternative to dark matter models we use generalized Jordan-Brans-Dicke scalar-vector-tensor (JBD-SVT) gravity model to study the behavior of the rotational velocities of test particles moving around galaxies. To do so we consider an…
Low surface brightness galaxies are an excellent laboratory where stars and baryonic matter act as tracers of the gravitational potential of the dark matter halo. If dark matter is modeled as a perfect fluid, then spherically symmetric and…
In the present investigation flat rotational curves of the galaxies are considered under the framework of brane-world models where the 4d effective Einstein equation has extra terms which arise from the embedding of the 3-brane in the $5d$…
In this work we propose a universal basic mass density and a universal basic metric inside dark matter halos in the framework of Einstein equations providing an analytical ground for learning about dark matter. In a previous work the…
In the present work, the Brans-Dicke (BD) theory of gravity is taken as a possible theory of k-essence. Then starting with the (already known) Brans-Dicke-Schwarzschild solution which can represent the gravitationally bound static…
We construct a model for galactic dark matter that arises as a solution of Einstein gravity, and is a Bertrand space-time matched with an external Schwarzschild metric. This model can explain galactic rotation curves. Further, we study…
We discuss a model in which the fundamental scale of gravity is restricted to 10^{-3} eV. An observable modification of gravity occurs simultaneously at the Hubble distance and at around 0.1 mm. These predictions can be tested both by the…
We present a detailed investigation of the properties of the galactic rotation curves in the Weyl geometric gravity model, in which the gravitational action is constructed from the square of the Weyl curvature scalar, and of the strength of…
For conformally invariant gravity theories defined on Riemannian spacetime and having the Schwarzschild--de-Sitter (SdS) metric as a solution in the Einstein gauge, we consider whether one may conformally rescale this solution to obtain…
On the base of an exact solution for the static spherically symmetric Einstein equations with the quintessential dark matter, we explain the asymptotic behavior of rotation curves in spiral galaxies. The parameter of the quintessence state,…
A very general class of axially-symmetric metrics in general relativity (GR) that includes rotations is used to discuss the dynamics of rotationally-supported galaxies. The exact vacuum solutions of the Einstein equations for this extended…
We consider dark masses measured from kinematic tracers at discrete radii in galaxies for which baryonic contributions to overall potentials are either subtracted or negligible. Recent work indicates that rotation curves due to dark matter…
We look for spherically symmetric star or black hole solutions on a Randall-Sundrum brane from the perspective of the bulk. We take a known bulk solution, and analyse possible braneworld trajectories within it that correspond, from the…
The spacetime satisfying the flat curve condition for galaxies is shown to be the zero mass limit of the dilaton blackhole with an exponential potential. We derive the geodesic equations and by studying rotational curves and light…
We study the cosmology of a three-brane in a specific five-dimensional scalar-gravity (i.e. soft-wall) background, known as the linear dilaton background. We discover that the Friedmann equation of the brane-world automatically contains a…
The collision-free Boltzmann equation is used in the context of brane-$f(R)$ gravity to derive the virial theorem. It is shown that the virial mass is proportional to certain geometrical terms appearing in the Einstein field equations and…
We continue the study of the non-metric theory of gravity introduced in hep-th/0611182 and gr-qc/0703002 and obtain its general spherically symmetric vacuum solution. It respects the analog of the Birkhoff theorem, i.e., the vacuum…