Reference frame dependence of the local measurement of the Hubble constant

TL;DR

This paper explores how the motion of observers' reference frames can cause a measurable discrepancy in local Hubble constant measurements, potentially explaining part of the observed tension.

Contribution

It introduces a method to quantify the impact of observer motion on local Hubble constant measurements within FLRW spacetime.

Findings

Reference frame motion can contribute about 1.1% to Hubble constant discrepancy.

The estimated difference due to motion is approximately 0.81 km s$^{-1}$ Mpc$^{-1}$.

This effect is significant enough to be considered as an uncertainty in local Hubble constant measurements.

Abstract

Observations recently suggest $4.4\sigma$ discrepancy between Hubble constant measured locally and that inferred from cosmic microwave background in standard cosmology. Either standard cosmology or local measurement might expect something new. We investigate the possibility that the value of Hubble constants might be affected by observers' motional status in the local measurement. Using adapted coordinate for geodesic observers in FLRW space-time and constraints inferred from observation of cosmic shear, we find that the motional status of reference frame could contribute to about $1.1 \pm 0.3\%$ discrepancy of these Hubble constants. Namely, the difference is $\Delta H_0= 0.81\pm0.22$ km s$^{-1}$ Mpc$^{-1}$, if the locally measured Hubble constant is $ 74$ km s$^{-1}$ Mpc$^{-1}$. This effect seems not negligible as an uncertainty for local measurement of Hubble constant