arXiv subjects

S. Shahidi

Publications and source records attributed to S. Shahidi.

3 recordsLinked to original sources

arXiv2011

Anisotropy in Born-Infeld brane cosmology

The accelerated expansion of the universe together with its present day isotropy has posed an interesting challenge to the numerous model theories presented over the years to describe them. In this paper, we address the above questions in the context of a brane-world model where the universe is filled with a Born-Infeld matter. We show that in such a model, the universe evolves from a highly anisotropic state to its present isotropic form which has entered an accelerated expanding phase.

gr-qc↗

arXiv2009

Brane $f(\cal R)$ gravity

We consider a brane world scenario in which the bulk action is assumed to have the form of a generic function of the Ricci scalar $f(\mathcal{R})$ and derive the resulting Einstein field equations on the brane. In a constant curvature bulk a conserved geometric quantity appears in the field equations which can be associated with matter. We present cosmological and spherically symmetric solutions by assuming specific forms for $f(\mathcal{R})$ and show that the former can explain an accelerated expanding universe while the latter may account for galaxy rotation curves.

gr-qc↗

arXiv2009

Virial mass in DGP brane cosmology

We study the virial mass discrepancy in the context of a DPG brane-world scenario and show that such a framework can offer viable explanations to account for the mass discrepancy problem. This is done by defining a geometrical mass $\mathcal{N}$ that we prove to be proportional to the virial mass. Estimating $\mathcal{N}$ using observational data, we show that it behaves linearly with $r$ and has a value of the order of $M_{200}$, pointing to a possible resolution of the virial mass discrepancy. We also obtain the radial velocity dispersion of galaxy clusters and show that it is compatible with the radial velocity dispersion profile of such clusters. This velocity dispersion profile can be used to differentiate various models predicting the virial mass.

gr-qc↗