New Method to Determine the Hubble Parameter from Cosmological Energy-Density Measurements.

Area of Science:

• Cosmology
• Astrophysics
• Galaxy Evolution

Background:

• Accurate measurement of the Hubble parameter (H0) is crucial for understanding the universe's expansion rate.
• Discrepancies exist between H0 values derived from early and late universe observations.
• Existing methods often rely on the comoving sound horizon, introducing potential systematic uncertainties.

Purpose of the Study:

• To introduce a new, independent method for measuring the Hubble parameter (H0) using low-redshift large-scale structure observations.
• To provide a precise H0 measurement that is independent of the comoving sound horizon.
• To assess the consistency of the new measurement with existing H0 determinations.

Main Methods:

• Utilizing the baryon-to-photon ratio from primordial deuterium abundance and Big Bang Nucleosynthesis (BBN) to determine physical baryon density (Ωbh²).
• Measuring the baryon fraction (Ωb/Ωm) from galaxy clustering data (Baryon Oscillation Spectroscopic Survey - BOSS).
• Employing Alcock-Paczynski tests from baryon acoustic oscillations (BAO) and voids to constrain geometrical density (Ωm) and derive H0.

Main Results:

• A measurement of the Hubble parameter H0 = 67.1−5.3+6.3 km s⁻¹ Mpc⁻¹ was obtained.
• The results remained consistent across various analysis choices, including different methods for measuring baryonic signatures and the inclusion/exclusion of datasets like supernovae and voids.
• The derived H0 value is consistent with both distance-ladder and cosmic microwave background (CMB) measurements.

Conclusions:

• The new method provides a robust and independent measurement of the Hubble parameter.
• Future large-scale structure surveys are expected to significantly improve the precision of this H0 measurement.
• This technique offers a valuable complementary approach to existing methods for cosmological parameter estimation.