COSMOLOGICAL DISTANCE MEASURE CONSTRAINTS ON THE DECELERATION PARAMETER

Abstract

Constraints on a parametrized deceleration parameter, q(a) = q0+ q1(1 - a), are investigated using cosmological observations of type Ia supernovae (SN Ia), baryon acoustic oscillations (BAOs) and cosmic microwave background (CMB) and observational Hubble data (OHD) which correspond to the cosmological distance measure. When a high redshift dataset of CMB is added in the SN + BAO + OHD case, a stronger constraint is obtained than for the lower redshift case, SN + BAO + OHD. The evolutions of the deceleration and Hubble parameters with respect to redshift z are reconstructed from cosmic observations. With cosmic observations as constraints, it is found that a smaller current deceleration parameter and a larger transition redshift are obtained in the SN + BAO + OHD case than in the SN + BAO + OHD + CMB case. In the SN + BAO + OHD + CMB case, slightly larger Hubble parameter values will be obtained than in the SN + BAO + OHD case.