Dark Energy and the Hubble Age

Abstract

I point out that an effective upper limit of approximately 20 Gyr (for a Hubble constant of 72 km/s/Mpc) or alternatively on the $H_0$-independent quantity $H_0{t}_0<1.47$, exists on the age of the Universe, essentially independent of the unknown equation of state of the dominant dark energy component in the Universe. Unless astrophysical constraints on the age of the Universe can convincingly reduce the upper limit to below this value no 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 may. For a constant value of $w$, a bound $H_0{t}_0<1.1$ gives a limit $w>-1.5$

4 pages, submitted to Ap. J. Lett (analytic asymptotic upper bound now added)

References in corpus (5)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Cosmological Results from High-z Supernovae
• New Constraints on ${\Omega }_M$, ${\Omega }_{\Lambda }$, and w from an Independent Set of Eleven High-Redshift Supernovae Observed with HST
• The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe
• Implications of the WMAP Age Measurement for Stellar Evolution and Dark Energy

Cited by in corpus (13)

• Interacting Dark Energy and Dark Matter: observational Constraints from Cosmological Parameters
• uvby-βphotometry of high-velocity and metal-poor stars XI. Ages of halo and old disk stars
• Model-independent dark energy test with sigma_8 using results from the Wilkinson Microwave Anisotropy Probe
• Two viable quintessence models of the Universe: confrontation of theoretical predictions with observational data
• Extended Born-Infeld Dynamics and Cosmology
• The Covariant Entropy Bound, Brane Cosmology, and the Null Energy Condition
• New Class of Dark Matter Objects and their Detection
• Variable G and $\Lambda$: scalar-tensor versus RG-improved cosmology
• A study on the dependence of the dimensionless Brans-Dicke parameter on the scalar field and their time dependence
• Dynamical age of the universe as a constraint on the parametrization of dark energy equation of state
• Some Enigmatic Aspects of the Early Universe
• The Standard Model, Dark Matter, and Dark Energy: From the Sublime to the Ridiculous
• A Critique of Drexler Dark Matter