Cosmological constraints on new agegraphic dark energy

In this work, we consider the cosmological constraints on the new agegraphic dark energy (NADE) proposed in arXiv: 0708.0884, by using the observational data of type Ia supernovae (SNIa), the shift parameter from cosmic microwave background (CMB) and the baryon acoustic oscillation (BAO) peak from large scale structures (LSS). Thanks to its special analytic features in the radiation-dominated and matter-dominated epochs, NADE is a single-parameter model in practice because once the single model parameter n is given, all other physical quantities of NADE can be determined correspondingly. The joint analysis gives the best-fit value (with 1σ uncertainty) n=2.716−0.109+0.111, and the derived Ωm0, Ωq0 and wq0 (with 1σ uncertainties) are 0.295−0.020+0.020, 0.705−0.020+0.020 and −0.794−0.005+0.006, respectively. In addition, we find that the coincidence problem could be solved naturally in the NADE model provided that n is of order unity.