Dark Energy and the Hubble Age | Zendy

Lawrence M. Krauss | Zendy

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Dark Energy and the Hubble Age

Author(s) -

Lawrence M. Krauss

Publication year - 2004

Publication title -

the astrophysical journal

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 2.376

H-Index - 489

eISSN - 1538-4357

pISSN - 0004-637X

DOI - 10.1086/382121

Subject(s) - hubble's law , physics , dark energy , age of the universe , cosmic microwave background , equation of state , astrophysics , limit (mathematics) , universe , supernova , metric expansion of space , cosmology , cosmological constant , astronomy , theoretical physics , quantum mechanics , mathematical analysis , mathematics , anisotropy

I point out that an effective upper limit of approximately 20 Gyr (for aHubble constant of 72 km/s/Mpc) or alternatively on the $H_0$-independentquantity $H_0t_0 < 1.47$, exists on the age of the Universe, essentiallyindependent of the unknown equation of state of the dominant dark energycomponent in the Universe. Unless astrophysical constraints on the age of theUniverse can convincingly reduce the upper limit to below this value no usefullower limit on the equation of state parameter $w$ for this component can beobtained. Direct dating by stars does not provide a useful constraint, butmodel-dependent cosmological limits from supernovae and the CMB observationsmay. For a constant value of $w$, a bound $H_0t_0 < 1.1$ gives a limit $ w>-1.5$Comment: 4 pages, submitted to Ap. J. Lett (analytic asymptotic upper bound now added

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