### Abstract

I point out that an effective upper limit of approximately 20(0.2/ω_{m})^{1/2} Gyr (for a Hubble constant of 72 km s^{-1} Mpc^{-1}), or alternatively, 1.49(0. 2/ω_{m})^{1/2} for the H_{0}-independent quantity H_{0}t_{0}, exists on the age of the universe, essentially independent of the unknown equation of state of the dominant dark energy component in the universe. If astrophysical constraints on the age of the universe can convincingly reduce the upper limit to well below this value, a useful lower limit on the equation of state parameter w for this component can be obtained. Direct dating by stars does not provide a useful constraint, but model-dependent cosmological limits from supernovae and the CMB observations can do so.

Original language | English (US) |
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Pages (from-to) | 481-483 |

Number of pages | 3 |

Journal | Astrophysical Journal |

Volume | 604 |

Issue number | 2 I |

DOIs | |

State | Published - Apr 1 2004 |

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### Keywords

- Cosmological parameters
- Cosmology: theory
- Equation of state
- Galaxy: fundamental parameters
- Gravitation

### ASJC Scopus subject areas

- Astronomy and Astrophysics
- Space and Planetary Science

### Cite this

*Astrophysical Journal*,

*604*(2 I), 481-483. https://doi.org/10.1086/382121