A gigaparsec-scale local void and the Hubble tension

TL;DR

This paper investigates whether a large, gigaparsec-scale local void could resolve the Hubble tension by affecting cosmological observations, proposing a model with specific parameters that may alleviate the discrepancy.

Contribution

It introduces a model of a gigaparsec-scale local void produced by multi-stream inflation to address the Hubble tension, analyzing its observational impacts.

Findings

A 1.7 Gpc scale void can ease the Hubble tension.

The void's boundary width is 0.7 Gpc with a density contrast of -0.14.

The model impacts supernovae, BAO, and kSZ observations.

Abstract

We explore the possibility of using a gigaparsec-scale local void to reconcile the Hubble tension. Such a gigaparsec-scale void can be produced by multi-stream inflation where different parts of the observable universe follow different inflationary trajectories. The impact of such a void for cosmological observations is studied, especially those involving supernovae, Baryon Acoustic Oscillations (BAO) and the kinetic Sunyaev-Zel'dovich (kSZ) effect. As a benchmark model, a 1.7Gpc scale with boundary width 0.7Gpc and density contrast -0.14 may ease the Hubble tension.