arXiv subjects

M. Heydari-Fard

Publications and source records attributed to M. Heydari-Fard.

7 recordsLinked to original sources

arXiv2019

Perihelion advance and trajectory of charged test particles in Reissner-Nordstrom field via the higher-order geodesic deviations

By using the higher-order geodesic deviation equations for charged particles, we apply the method described by Kerner et.al. to calculate the perihelion advance and trajectory of charged test particles in the Riessner-Nordstrom spacetime. The effect of charge on the perihelion advance is studied and compared the results with those obtained earlier via the perturbation method. The advantage of this approximation method is to provide a way to calculate the perihelion advance and orbit of planets in the vicinity of massive and compact objects without considering Newtonian and post-Newtonian approximation.

gr-qc↗

arXiv2007

Generalized Chaplygin gas as geometrical dark energy

The generalized Chaplygin gas provides an interesting candidate for the present accelerated expansion of the universe. We explore a geometrical explanation for the generalized Chaplygin gas within the context of brane world theories where matter fields are confined to the brane by means of the action of a confining potential. We obtain the modified Friedmann equations, deceleration parameter and age of the universe in this scenario and show that they are consistent with the present observational data.

gr-qc↗

arXiv2007

Brane-World Black Hole Solutions via a Confining Potential

Using a confining potential, we consider spherically symmetric vacuum (static black hole) solutions in a brane-world scenario. Working with a constant curvature bulk, two interesting cases/solutions are studied. A Schwarzschild-de Sitter black hole solution similar to the standard solution in the presence of a cosmological constant is obtained which confirms the idea that an extra term in the field equations on the brane can play the role of a positive cosmological constant and may be used to account for the accelerated expansion of the universe. The other solution is one in which we can have a proper potential to explain the galaxy rotation curves without assuming the existence of dark matter and without working with new modified theories (modified Newtonian dynamics).

gr-qc↗

arXiv2007

Accelerating universe in brane gravity with a confining potential

We construct the Einstein field equations on a 4-dimensional brane embedded in an $m$-dimensional bulk where the matter fields are confined to the brane by means of a confining potential. As a result, an extra term in the Friedmann equation in a $m$-dimensional bulk appears that may be interpreted as the X-matter, providing a possible phenomenological explanation for the acceleration of the universe. The study of the relevant observational data suggests good agreement with the predictions of this model.

gr-qc↗

arXiv2007

Anisotropic brane gravity with a confining potential

We consider an anisotropic brane world with Bianchi type I and V geometries where the mechanism of confining the matter on the brane is through the use of a confining potential. The resulting equations on the anisotropic brane are modified by an extra term that may be interpreted as the x-matter, providing a possible phenomenological explanation for the accelerated expansion of the universe. We obtain the general solution of the field equations in an exact parametric form for both Bianchi type I and V space-times. In the special case of a Bianchi type I the solutions of the field equations are obtained in an exact analytic form. Finally, we study the behavior of the observationally important parameters.

gr-qc↗

arXiv2007

Gauss-Bonnet brane gravity with a confining potential

A brane scenario is envisaged in which the $m$-dimensional bulk is endowed with a Gauss-Bonnet term and localization of matter on the brane is achieved by means of a confining potential. The resulting Friedmann equations on the brane are modified by various extra terms that may be interpreted as the X-matter, providing a possible phenomenological explanation for the accelerated expansion of the universe. The age of the universe in this scenario is studied and shown to be consistent with the present observational data.

gr-qc↗

arXiv2005

Worldline deviations of charged spinning particles

The geodesic deviation equation is generalized to worldline deviation equations describing the relative accelerations of charged spinning particles in the framework of Dixon-Souriau equations of motion.

gr-qc↗