A parametric reconstruction of the deceleration parameter

Abstract

The present work is based on a parametric reconstruction of the deceleration parameter q(z) in a model for the spatially flat FRW universe filled with dark energy and non-relativistic matter. In cosmology, the parametric reconstruction technique deals with an attempt to build up a model by choosing some specific evolution scenario for a cosmological parameter and then estimate the values of the parameters with the help of different observational datasets. In this paper, we have proposed a logarithmic parametrization of q(z) to probe the evolution history of the universe. Using the type Ia supernova, baryon acoustic oscillation and the cosmic microwave background datasets, the constraints on the arbitrary model parameters q 0 and q 1 are obtained (within 1σ and 2σ confidence limits) by χ 2 -minimization technique. We have then reconstructed the deceleration parameter, the total EoS parameter ω tot , the jerk parameter and have compared the reconstructed results of q(z) with other well-known parametrizations of q(z). We have also shown that two model selection criteria (namely, the Akaike information criterion and Bayesian information criterion) provide a clear indication that our reconstructed model is well consistent with other popular models.

Phenomenological reconstruction of f(T) teleparallel gravity

“…It is reasonable to keep q 0 as measured in [16] assuming the Ω m (z l )-peak to occur at z l = 3, so we get q 1 ∼ −3.366, −1.525, −1.114 and −0.913 for the values N = 2 · · · 5, respectively. In this case, we plot the evolution f (T ) gravity, namely (54), as shown in Fig.…”

“…Using the above parametrization, the deceleration parameter (44) has been confronted with observational datasets, in particular JLA SNIa and BAO/CMB, whereas the best fit values of the free parameters q 0 and q 1 have been calculated up to 1σ [16]. In addition, it has been shown that, at present time z = 0, the above parametrization leads the deceleration parameter to have a value q = q 0 , while at large redshift one can obtain the matter dominant era, q = 1 2 , by using the constraint q 1 = 2q0−1 2 ln N .…”

“…3(c), we plot the evolution of the matter and the torsion density parameters according to the calculated values of the model parameters q 0 and q 1 as given in Ref. [16]. As shown by the plots, the matter density parameter 0 < Ω m (z) < 1 at large redshifts, then it peaks up at low redshifts crossing the unit boundary line at redshifts z ∼ 15.78, 17.96, 14.89 and 16.41 for the values N = 2 · · · 5, respectively.…”

“…In Table II, we summarize the results of model 1 according to the values of the model parameters q 0 and q 1 as given in Ref. [16] and by applying the matter density constraint (58).…”

“…(a) f (T ) gravity (b) w ef f evolution (c) Ωm, Ω T evolution (d) w T evolution The best fit values of Model 2 parameters (q0, q1) are taken according to the constraint (58). The model parameter q0 is kept fixed to it value as measured in[16], since it is compatible with the present values of other cosmological parameters. However, the model parameter q1 is recalculated to fulfill (58) as given on the plots; (a) The f (T ) gravity matches ΛCDM at large redshifts on the contrary to the corresponding plots inFig.…”