### 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) |
---|---|

Pages (from-to) | 481-483 |

Number of pages | 3 |

Journal | Astrophysical Journal |

Volume | 604 |

Issue number | 2 I |

DOIs | |

State | Published - Apr 1 2004 |

Externally published | Yes |

### Fingerprint

### Keywords

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

### ASJC Scopus subject areas

- Space and Planetary Science

### Cite this

*Astrophysical Journal*,

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

**Dark energy and the Hubble age.** / Krauss, Lawrence.

Research output: Contribution to journal › Article

*Astrophysical Journal*, vol. 604, no. 2 I, pp. 481-483. https://doi.org/10.1086/382121

}

TY - JOUR

T1 - Dark energy and the Hubble age

AU - Krauss, Lawrence

PY - 2004/4/1

Y1 - 2004/4/1

N2 - I point out that an effective upper limit of approximately 20(0.2/ωm)1/2 Gyr (for a Hubble constant of 72 km s-1 Mpc-1), or alternatively, 1.49(0. 2/ωm)1/2 for the H0-independent quantity H0t0, 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.

AB - I point out that an effective upper limit of approximately 20(0.2/ωm)1/2 Gyr (for a Hubble constant of 72 km s-1 Mpc-1), or alternatively, 1.49(0. 2/ωm)1/2 for the H0-independent quantity H0t0, 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.

KW - Cosmological parameters

KW - Cosmology: theory

KW - Equation of state

KW - Galaxy: fundamental parameters

KW - Gravitation

UR - http://www.scopus.com/inward/record.url?scp=2642559383&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=2642559383&partnerID=8YFLogxK

U2 - 10.1086/382121

DO - 10.1086/382121

M3 - Article

VL - 604

SP - 481

EP - 483

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 I

ER -