270 research outputs found
Primordial black hole production during preheating in a chaotic inflationary model
In this paper we review the production of primordial black holes (PBHs)
during preheating after a chaotic inflationary model. All relevant equations of
motion are solved numerically in a modified version of HLattice, and we then
calculate the mass variance to determine structure formation during preheating.
It is found that production of PBHs can be a generic result of the model, even
though the results seem to be sensitive to the values of the smoothing scale.
We consider a constraint for overproduction of PBHs that could uncover some
stress between inflation-preheating models and observations.Comment: 6 pages, 5 figures. Prepared for the conference proceedings of the
9th Mexican School on Gravitation and Mathematical Physics : Cosmology for
the XXI Century: Inflation, Dark Matter and Dark Energ
Lukewarm dark matter: Bose condensation of ultralight particles
We discuss the thermal evolution and Bose-Einstein condensation of
ultra-light dark matter particles at finite, realistic cosmological
temperatures. We find that if these particles decouple from regular matter
before Standard model particles annihilate, their temperature will be about 0.9
K. This temperature is substantially lower than the temperature of CMB
neutrinos and thus Big Bang Nucleosynthesis remains unaffected. In addition the
temperature is consistent with WMAP 7-year+BAO+H0 observations without
fine-tuning. We focus on particles of mass of eV, which have
Compton wavelengths of galactic scales. Agglomerations of these particles can
form stable halos and naturally prohibit small scale structure. They avoid
over-abundance of dwarf galaxies and may be favored by observations of dark
matter distributions. We present numerical as well as approximate analytical
solutions of the Friedmann-Klein-Gordon equations and study the cosmological
evolution of this scalar field dark matter from the early universe to the era
of matter domination. Today, the particles in the ground state mimic
presureless matter, while the excited state particles are radiation like.Comment: 6 pages, 2 figures, Accepted by ApJ Letters, Includes Referee Input
Cosmological constraints for a two brane-world system with single equation of state
We present the study of two 3-brane system embedded in a 5-dimensional
space-time in which the fifth dimension is compactified on a
orbifold. Assuming isotropic, homogeneous, and static branes, it can be shown
that the dynamics of one brane is dominated by the other one when the metric
coefficients have a particular form. We study the resulting cosmologies when
one brane is dominated by a given single-fluid component.Comment: This work was presented at the VIII Taller of the DGFM, Tuxtla
Gutierrez, Chiapas, Mexico noviembre 22-26, 201
Supersymmetric classical cosmology
In this work a supersymmetric cosmological model is analyzed in which we
consider a general superfield action of a homogeneous scalar field
supermultiplet interacting with the scale factor in a supersymmetric FRW model.
There appear fermionic superpartners associated with both the scale factor and
the scalar field, and classical equations of motion are obtained from the
super-Wheeler-DeWitt equation through the usual WKB method. The resulting
supersymmetric Einstein-Klein-Gordon equations contain extra radiation and
stiff matter terms, and we study their solutions in flat space for different
scalar field potentials. The solutions are compared to the standard case, in
particular those corresponding to the exponential potential, and their
implications for the dynamics of the early Universe are discussed in turn.Comment: 9 pages, 4 eps figures, uses RevTe
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