Joel C. Carvalho

Nonsingular FRW cosmology and nonlinear electrodynamics

The possibility to avoid the cosmic initial singularity as a consequence of nonlinear effects on the Maxwell eletromagnetic theory is discussed. For a flat FRW geometry we derive the general nonsingular solution supported by a magnetic field plus a cosmic fluid and a nonvanishing vacuum energy density. The nonsingular behavior of solutions with a time-dependent

Probing interaction in the dark sector

\Lambda(t)

NONLINEARITY OF ELECTRODYNAMICS AS A SOURCE OF MATTER CREATION IN A FLAT FRW COSMOLOGY

-term are also examined. As a general result, it is found that the functional dependence of

SOLUTIONS OF COSMOLOGICAL MODELS WITH VARYING SPEED OF LIGHT

\Lambda(t)

Cosmological gravitons and the expansion dynamics during the matter age

can uniquely be determined only if the magnetic field remains constant. All these models are examples of bouncing universes which may exhibit an inflationary dynamics driven by the nonlinear corrections of the magnetic field.

The effects of large-scale motion on the regeneration of turbulent dynamo

A phenomenological attempt at alleviating the so-called coincidence problem is to allow the dark matter and dark energy to interact. By assuming a coupled quintessence scenario characterized by an interaction parameter

The infrared emission of quasars

\epsilon

The angular dimensions of extragalactic radio sources

, we investigate the precision in the measurements of the expansion rate

Cosmological consequences of a time-dependent Λ term

H(z)

On detecting interactions in the dark sector with H ( z ) data

required by future experiments in order to detect a possible deviation from the standard