2 research outputs found
Axionic extension of the Einstein-aether theory: How does dynamic aether regulate the state of axionic dark matter?
In the framework of axionic extension of the Einstein-aether theory we
establish the model, which describes a stiff regulation of the behavior of
axionic dark matter by the dynamic aether. The aether realizes this procedure
via the modified Higgs potential, designed for modeling of nonlinear
self-interaction of pseudoscalar (axion) field; the modification of this
potential is that its minima are not fixed, and their positions and depths
depend now on the square of the covariant derivative of the aether velocity
four-vector. Exact solutions to the master equations, modified correspondingly,
are obtained in the framework of homogeneous isotropic cosmological model. The
effective equation of state for axionic dark matter is of the stiff type.
Homogeneous perturbations of the pseudoscalar (axion) field, of the Hubble
function and of the scale factor are shown to fade out with cosmological time,
there are no growing modes, the model of stiff regulation is stable.Comment: 12 pages, 0 figures, revised version published in Physics of the Dark
Univers
Interaction of the Cosmic Dark Fluid with Dynamic Aether: Parametric Mechanism of Axion Generation in the Early Universe
We consider an isotropic homogeneous cosmological model with five interacting
elements: first, the dynamic aether presented by a unit timelike vector field,
second, the pseudoscalar field describing an axionic component of the dark
matter, third, the cosmic dark energy, described by a rheologic fluid, fourth,
the non-axionic dark matter coupled to the dark energy, fifth, the gravity
field. We show that the early evolution of the Universe described by this model
can include two specific epochs: the first one can be characterized as a
super-inflation, the second epoch is associated with an oscillatory regime. The
dynamic aether carries out a regulatory mission; the rheologic dark fluid
provides the specific features of the spacetime evolution. The oscillations of
the scale factor and of the Hubble function are shown to switch on the
parametric (Floquet - type) mechanism of the axion number growth.Comment: 21 pages, 4 figures, accepted for publication in Symmetry, Special
Issue: Fundamental Aspects of Theoretical Physics - Memorial Issue for Prof.
Dr. Weinber