No CrossRef data available.
Published online by Cambridge University Press: 19 July 2016
The age of a high-redshift QSO can constrain the cosmology by placing a limit on the cosmological time. We use the observed FeII (UV+optical)/MgIIλ2798 flux ratio from the broad-line gas of a QSO at z=3.62 to estimate the abundance ratio [Mg/Fe] and predict that the QSO is at least 1.3 Gyr old from the chemical analysis using the abundance ratio [Mg/Fe] as a cosmic clock. Our result favors a nonzero cosmological constant and thus conflicts with a flat, matter-dominated universe.