Calibrating the cosmic distance scale ladder: the role of the sound horizon scale and the local expansion rate as distance anchors

TL;DR

This paper constructs a cosmology-independent cosmic distance ladder using supernovae and baryon acoustic oscillations, calibrating with local $H_0$ and the sound horizon scale, to measure the universe's expansion and key cosmological parameters.

Contribution

It introduces a method to calibrate the cosmic distance ladder using both local $H_0$ and the sound horizon scale without relying on early universe assumptions.

Findings

Consistent $H_0$ values from both calibration methods.

Sound horizon scale uncertainty is smaller when used as an anchor.

Derived $r_d$ and $H_0$ values agree with Planck CMB results.

Abstract

We exploit cosmological-model independent measurements of the expansion history of the Universe to provide a cosmic distance ladder. These are supernovae type Ia used as standard candles (at redshift between 0.01 and 1.3) and baryon acoustic oscillations (at redshifts between 0.1 and 0.8) as standard rulers. We calibrate (anchor) the ladder in two ways: first using the local $H_0$ value as an anchor at $z$ = 0 (effectively calibrating the standard candles) and secondly using the cosmic microwave background-inferred sound-horizon scale as an anchor (giving the standard ruler length) as an inverse distance ladder. Both methods are consistent, but the uncertainty in the expansion history $H(z)$ is smaller if the sound horizon scale is used. We present inferred values for the sound horizon at radiation drag $r_d$ which do not rely on assumptions about the early expansion history nor on cosmic microwave background measurements but on the cosmic distance ladder and baryon acoustic oscillations measurements. We also present derived values of $H_0$ from the inverse distance ladder and we show that they are in very good agreement with the extrapolated value in a $\Lambda$CDM model from Planck cosmic microwave background data.