Partially Acoustic Dark Matter Cosmology and Cosmological Constraints

TL;DR

This paper explores modifications to the standard cosmological model by introducing acoustic dark matter and dark radiation to address tensions between CMB, weak lensing, and local Hubble constant measurements, analyzing their effectiveness and limitations.

Contribution

It proposes and compares models with acoustic dark matter and dark radiation to alleviate cosmological measurement tensions, highlighting their partial success and inherent constraints.

Findings

Models can relieve Hubble and lensing tensions separately.

Adding cold dark matter is necessary to preserve CMB peak sharpness.

Complete resolution of tensions remains challenging due to model constraints.

Abstract

Observations of the cosmic microwave background (CMB) together with weak lensing measurements of the clustering of large scale cosmological structures and local measurements of the Hubble constant pose a challenge to the standard $\Lambda$CDM cosmological model. On one side CMB observations imply a Hubble constant that is lower than local measurements and an amplitude of the lensing signal that is higher than direct measurements from weak lensing surveys. We investigate a way of relieving these tensions by adding dark radiation tightly coupled to an acoustic part of the dark matter sector and compare it to massive neutrino solutions. While these models offer a way of separately relieving the Hubble and weak lensing tensions they are prevented from fully accommodating both at the same time since the CMB requires additional cold dark matter when adding acoustic dark matter or massive neutrinos to preserve the same sharpness of the acoustic peaks which counteracts the desired growth suppression.