AWhat changed
Jimenez, Verde, Treu and Stern used the upper age envelope of selected SDSS galaxies to estimate the low-redshift expansion rate, finding H₀ = 69 ± 12 km s⁻¹ Mpc⁻¹ in their 2003 analysis. Simon, Verde and Jimenez subsequently combined selected galaxy spectra, including previously analyzed objects and new survey data, to estimate H(z) at nine redshifts and fit a parameterized dark-energy potential; the resulting potential was consistent with a constant within the stated uncertainties.
Scientific scope
Jimenez, Verde, Treu and Stern used the upper age envelope of selected SDSS galaxies to estimate the low-redshift expansion rate, finding H₀ = 69 ± 12 km s⁻¹ Mpc⁻¹ in their 2003 analysis. Simon, Verde and Jimenez subsequently combined selected galaxy spectra, including previously analyzed objects and new survey data, to estimate H(z) at nine redshifts and fit a parameterized dark-energy potential; the resulting potential was consistent with a constant within the stated uncertainties. Stellar ages depend on population-synthesis fits, passive-evolution assumptions and galaxy selection, not direct clocks. The 2003 low-redshift fit extends to z = 0.17 at effective z = 0.09 and uses an approximately 4% extrapolation to H₀ in its reference cosmology. The later work reuses earlier galaxy data and the earlier low-redshift determination; the two are not independent detections. Its galaxy sample is small, and dark-energy potential reconstruction assumes spatial flatness, chosen parameterization and matter-density priors. Consistency with a constant potential does not exclude evolution. Forecasts for future surveys are not achieved results.
Evidence
The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. Stellar ages depend on population-synthesis fits, passive-evolution assumptions and galaxy selection, not direct clocks. The 2003 low-redshift fit extends to z = 0.17 at effective z = 0.09 and uses an approximately 4% extrapolation to H₀ in its reference cosmology. The later work reuses earlier galaxy data and the earlier low-redshift determination; the two are not independent detections. Its galaxy sample is small, and dark-energy potential reconstruction assumes spatial flatness, chosen parameterization and matter-density priors. Consistency with a constant potential does not exclude evolution. Forecasts for future surveys are not achieved results.
Contributors
- The named authors in the research record · SCIENCE: These are the listed authors of the cited contribution sources. Paper authorship does not quantify individual effort. An incomplete list is explicitly marked; same names are not automatically merged.
- Constraints on the equation of state of dark energy and the Hubble constant from stellar ages and the CMB
- Constraints on the redshift dependence of the dark energy potential
Provisional WRS assessment, edition 2026-10-28.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.
Full scientific record · Browse contribution grades · Request a correction