Abstract
Cosmological evolution driven incorporating continuous particle creation by the time-varying gravitational field is investigated. We consider a spatially flat, homogeneous and isotropic universe with two matter fluids in the context of general relativity. One fluid is endowed with gravitationally induced “adiabatic” particle creation, while the second fluid simply satisfies the conservation of energy. We show that the dynamics of the two fluids is entirely controlled by a single nonlinear differential equation involving the particle creation rate, Gamma (t). We consider a very general particle creation rate, Gamma (t) , that reduces to several special cases of cosmological interest, including Gamma = constant, Gamma propto 1/H^{n} (nin mathbb {N}), Gamma propto exp (1/H). Finally, we present singular algebraic solutions of the gravitational field equations for the two-fluid particle creation models and discuss their stability.
Highlights
It is useful to elaborate on the connection between the quantum particle production studied in references like [1– 115 Page 2 of 9Eur
Our model described in Eq (6) below is a cosmology with a classical bulk viscous stress that can induce particle creation in the form of particle density increases
We find that the dynamics of the universe is governed by a nonlinear differential equation which is dependent on the choice of the particle creation rate
Summary
It is useful to elaborate on the connection between the quantum particle production studied in references like [1–. 4] and the classic picture of particle production that we use here by introducing a non-adiabatic term in the conservation equation for one of our fluids In effect, this is equivalent to endowing that fluid with a bulk viscosity [27], which is the only form of dissipative stress allowed in the isotropic models. We will consider a spatially flat homogeneous and isotropic universe where the gravitational sector is described by general relativity and the total matter sector is divided into two fluids where one fluid (named as fluid I) is endowed with “adiabatic” particle production process and the second fluid (fluid II) is independently conserved With this set up, we find that the dynamics of the universe is governed by a nonlinear differential equation which is dependent on the choice of the particle creation rate.
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