A measurement of $H_0$ from DESI DR1 using energy densities

TL;DR

This paper introduces a novel low-redshift method to measure the Hubble constant by calibrating the Universe's energy density using DESI DR1 data, independent of standard rulers and robust to early dark energy modifications.

Contribution

It presents a new approach to measure H_0 by combining energy density calibrations with galaxy clustering and BBN constraints, validated on simulations and theory.

Findings

Measured H_0 = 69.0 ± 2.5 km/s/Mpc, consistent with existing values.

Method is robust to early dark energy and pre-recombination modifications.

Validated approach on simulations and theoretical models.

Abstract

We present a new measurement of the Hubble constant, independent of standard rulers and robust to pre-recombination modifications such as Early Dark Energy (EDE), obtained by calibrating the total energy density of the Universe. We start using the present-day photon density as an anchor, and use the baryon-to-photon ratio from Big Bang Nucleosynthesis based measurements and the baryon-to-matter ratio from the baryons' imprint on galaxy clustering to translate to a physical matter density at present day. We then compare this to measurements of the ratio of the matter density to the critical density ($\Omega_{\mathrm{m}}$), calculated using the relative positions of the baryon acoustic oscillations, to measure the critical density of the universe and hence $H_0$. The important measurements of the evolution of the energy density all happen at low redshift, so we consider this a low-redshift measurement. We validate our method both on a suite of $N$-body mocks and on noiseless theory vectors generated across a wide range of Hubble parameters in both $\Lambda$CDM and EDE cosmologies. Using DESI DR1 data combined with the angular CMB acoustic scale and the latest BBN constraints, we find $H_0 = 69.0 \pm 2.5$ km s$^{-1}$ Mpc$^{-1}$, consistent with existing early and late-time determinations of the Hubble constant. We consider the impact of non-standard dark energy evolution on our measurement. Future data, including that from further iterations of DESI and from Euclid, will add to these results providing a powerful test of the Hubble tension.