Observational constraints on Hubble constant and deceleration parameter in power-law cosmology

Abstract

In this paper, we show that the expansion history of the Universe in power-law cosmology essentially depends on two crucial parameters, namely the Hubble constant H 0 and deceleration parameter q. We find the constraints on these parameters from the latest H(z) and SNe Ia data. At 1σ level the constraints from H(z) data are obtained as and kms -1Mpc -1, while the constraints from the Type Ia supernovae (SNe Ia) data are and kms -1Mpc -1. We also perform the joint test using H(z) and SNe Ia data, which yields the constraints and kms -1Mpc -1. The estimates of H 0 are found to be in close agreement with some recent probes carried out in the literature. The analysis reveals that the observational data successfully describe the cosmic acceleration within the framework of power-law cosmology. We find that the power-law cosmology accommodates well the H(z) and SNe Ia data. We also test the power-law cosmology using the primordial nucleosynthesis, which yields the constraints q≳ 0.72 and H 0≲ 41.49kms -1Mpc -1. These constraints are found to be inconsistent with the ones derived from the H(z) and SNe Ia data. We carry out the statefinder analysis, and find that the power-law cosmological models approach the standard Λ cold dark matter (ΛCDM) model as q→-1. Finally, we conclude that despite having several good features power-law cosmology is not a complete package for the cosmological purposes. © 2012 The Author Monthly Notices of the Royal Astronomical Society © 2012 RAS.