An accelerating cosmology without dark energy

Abstract

The negative pressure accompanying gravitationally-induced particle creation can lead to a cold dark matter (CDM) dominated, accelerating Universe (Lima et al. 1996 [1]) without requiring the presence of dark energy or a cosmological constant. In a recent study Lima et al. 2008 [2] (LSS) demonstrated that particle creation driven cosmological models are capable of accounting for the SNIa observations [3] of the recent transition from a decelerating to an accelerating Universe. Here we test the evolution of such models at high redshift using the constraint on zeq, the redshift of the epoch of matter -radiation equality, provided by the WMAP constraints on the early Integrated Sachs-Wolfe effect (ISW) [4]. Since the contribution of baryons and radiation was ignored in the work of LSS, we include them in our study of this class of models. The parameters of these more realistic models with continuous creation of CDM is tested and constrained at widely-separated epochs (z ≈ zeq and z ≈ 0) in the evolution of the Universe. This comparison reveals a tension between the high redshift CMB constraint on zeq and that which follows from the low redshift SNIa data, challenging the viability of this class of models. 95.35.+d,95.30.Tg

Dark energy, matter creation and curvature

“…Using the γ model, it is possible to get a good fit (χ red = 0.994) using only SNIa+BAO, however once we add the CMB constraint, it worsens the fit (χ red = 1.32). It is therefore clear why in [15] the authors add an explicit contribution for baryons. Adding baryonic dark matter with Ω B = 0.042 in the previous models, enable us to obtain better best fit parameters for the models that, for instance modifying Fig.…”

“…They explicitly show that previous models considered [14], does not exhibit the transition, and study the observational constraints on the model parameters. Also in [15] the authors modified slightly the model, adding explicitly a baryonic contribution, which enable them to have a transition from decelerated to accelerated expansion always.…”

Dynamical analysis of an interacting dark energy model in the framework of a particle creation mechanism

“…This model can successfully mimic the ΛCDM cosmology [48][49][50][51][52]. Historically, in 1939, Schrodinger [53] introduced a microscopic description of particle production in an expanding universe where gravity plays a crucial role.…”

Cosmology from Kaluza-Klein gravitational model

“…Others models of dark energy which will not be appreciated in this work are: φ CDM model [8], Chaplygin gas [9], CCDM model [10], XCDM model [11], Λ(t)CDM model [12], inhomogeneous models [13], f (R) theories [14] and kinematic models [15].…”