New Globular Cluster Age Estimates and Constraints on the Cosmic Equation of State and The Matter Density of the Universe

TL;DR

This paper provides new lower limits on the universe's age based on globular cluster data, supporting a dark energy-dominated cosmology and constraining matter density and equation of state parameters.

Contribution

It introduces updated globular cluster age estimates that, combined with cosmological data, reinforce the evidence for dark energy and refine constraints on cosmological parameters.

Findings

Universe's age lower limit is 11 Gyr at 95% confidence.

Supports a cosmological constant (w=-1) as consistent with data.

Constraints: w < -0.4 and Omega_matter < 0.38 at 68% confidence.

Abstract

New estimates of globular cluster distances, combined with revised ranges for input parameters in stellar evolution codes and recent estimates of the earliest redshift of cluster formation allow us to derive a new 95% confidence level lower limit on the age of the Universe of 11 Gyr. This is now definitively inconsistent with the expansion age for a flat Universe for the currently allowed range of the Hubble constant unless the cosmic equation of state is dominated by a component that violates the strong energy condition. This solidifies the case for a dark energy-dominated universe, complementing supernova data and direct measurements of the geometry and matter density in the Universe. The best-fit age is consistent with a cosmological constant-dominated (w=pressure/energy density = -1) universe. For the Hubble Key project best fit value of the Hubble Constant our age limits yields the constraints w < -0.4 and Omega_matter < 0.38 at the 68 % confidence level, and w < -0.26 and Omega_matter < 0.58 at the 95 % confidence level.