New limits on $Ω_Λ$ and $Ω_M$ from old galaxies at high redshift

  • 20 February 1999
Abstract
The ages of two old galaxies (53W091, 53W069) at high redshifts are used to constrain the value of the cosmological constant in a flat universe ($\Lambda$CDM) and the density parameter $\Omega_M$ in Friedmann-Robertson-Walker (FRW) models with no $\Lambda$-term. In the case of $\Lambda$CDM models, the quoted galaxies yield two lower limits for the vacuum energy density parameter, $\Omega_\Lambda \geq 0.42$ and $\Omega_\Lambda \geq 0.5$, respectively. Although compatible with the limits from statistics of gravitational lensing (SGL) and cosmic microwave background (CMB), these lower bounds are more stringent than the ones recently determined using supernovae type Ia (SNe Ia) as standard candles. For matter dominated universes ($\Omega_\Lambda=0$), the existence of these galaxies imply that the universe is open with the matter density parameter constrained by $\Omega_M \leq 0.45$ and $\Omega_M \leq 0.37$, respectively. In particular, these results disagree completelly with the analysis of field galaxies which gives a lower limit $\Omega_M \geq 0.40$.

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