Inflationary cosmology and thermodynamics

Abstract

We present a simple and thermodynamically consistent cosmology with a phenomenological model of quantum creation of radiation due to vacuum decay. Thermodynamics and Einstein's equations lead to an equation in which H is determined by the particle number N . The model is completed by specifying the particle creation rate Γ =Ṅ /N , which leads to a second-order evolution equation for H. We propose a simple Γ that is naturally defined and that conforms to the thermodynamical conditions: (a) the entropy production rate starts at a maximum; (b) the initial vacuum (for radiation) is a non-singular regular vacuum; and (c) the creation rate is initially higher than the expansion rate H, but then falls below H. The evolution equation for H then has a remarkably simple exact solution, in which a non-adiabatic inflationary era exits smoothly to the radiation era, without a reheating transition. For this solution, we give exact expressions for the cosmic scale factor, energy density of radiation and vacuum, temperature, entropy and super-horizon scalar perturbations.PACS numbers: 9880C, 9880H, 9530T, 0540

Cosmological particle production, causal thermodynamics, and inflationary expansion

“…In particular, one may think here of quantum particle production out of the gravitational field [12][13][14]. The manifestation of cosmological particle creation as an effective bulk pressure has initiated a series of papers discussing a fluid phenomenological approach to cosmological particle production [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The present paper will mainly explore this second aspect as well.…”

Cosmological models with dynamicalΛin scalar-tensor theories

“…This old idea has received a lot of attention (see e.g. [4]- [43]). What people have in mind is to make the vacuum energy dynamical.…”

Complete cosmic scenario from inflation to late time acceleration: Nonequilibrium thermodynamics in the context of particle creation

“…Now, according to Gunzig et al [34], the simplest choice satisfying the above requirements is that the particle creation rate is proportional to the energy density, i.e., Γ = 3β…”