Gravitational particle creation for dark matter and reheating

Gravitational Fields and Dark Matter

when the curvature of space is negative (L is the Lobachevskij constant). For obtaining a potential of Newton (or Coulomb) It is necessary to put c2 = −c1/L, L → ∞ (c2 = −c1/R, R → ∞). Let’s consider hereinafter, that at availability of the space curvature to be obliged non-zero, owing to what the Newton potential should be exchanged by a potential (1), in which c2 = −c1/L And to which one actu...

Dark Matter and Gravitational Lensing

The last decade has shown a considerable development of gravitational lensing for cosmology because it probes the amount and the nature of dark matter, and provides information on the density parameter Ω, the cosmological constant Λ and the Hubble constant Ho. Therefore, gravitational lensing can constrain the cosmological scenario which gave birth to the Universe as it appears today. The ongoi...

Particle Candidates for Dark Matter

Gravitational Excitons as Dark Matter ∗

In earlier work it was pointed out that for warped product spacetimes the conformal (geometrical moduli) excitations of the internal compactified factor spaces should be observable as massive scalar fields in the external spacetime. Here we show that these scalar fields (gravitational excitons) describe weakly interacting particles and can be considered as dark matter component. Masses of the g...

Kination-dominated Reheating and Cold Dark Matter Abundance

We consider the decay of a massive particle under the complete or partial domination of the kinetic energy density generated by a quintessential exponential model and we impose a number of observational constraints, originating from nucleosynthesis, the present acceleration of the universe and the dark-energy-density parameter. We show that the presence of kination causes a prolonged period dur...