Review of Solutions to the Cusp-Core Problem of the ΛCDM Model

Antonino Del Popolo,Morgan Le Delliou

doi:10.3390/galaxies9040123

Abstract

This review aims at proposing to the field an overview of the Cusp-core problem, including a discussion of its advocated solutions, assessing how each can satisfactorily provide a description of central densities. Whether the Cusp-core problem reflects our insufficient grasp on the nature of dark matter, of gravity, on the impact of baryonic interactions with dark matter at those scales, as included in semi-analytical models or fully numerical codes, the solutions to it can point either to the need for a paradigm change in cosmology, or to to our lack of success in ironing out the finer details of the ΛCDM paradigm.

Highlights

Notwithstanding the many successes of the concordance cosmology model, known as the ΛCDM model, fundamental issues remain open
The “cosmological constant fine tuning problem” emerges from the large discrepancy between the observed value of Λ and the huge values predicted by quantum field theories for the present quantum vacuum energy, the latter exceeding the former by more than 100 orders of magnitude [9,10,11]: the cosmological observation upper bounds are limited to ρΛ ' 10−47 GeV4, while the naive theoretical expectations obtain ρΛ ' 1071 GeV4
Since the first assessment by Öpik of the amount of matter surrounding our solar system through vertical star motion with respect to the plane of the ecliptic more than a century ago [288], current data indicates a dominant amount of matter should be in the form of dark matter (DM)

Summary

Introduction

Notwithstanding the many successes of the concordance cosmology model, known as the ΛCDM model, fundamental issues remain open. The “cosmological constant fine tuning problem” emerges from the large discrepancy between the observed value of Λ and the huge values predicted by quantum field theories for the present quantum vacuum energy, the latter exceeding the former by more than 100 orders of magnitude [9,10,11]: the cosmological observation upper bounds are limited to ρΛ ' 10−47 GeV4 , while the naive theoretical expectations obtain ρΛ ' 1071 GeV4. This is the most extreme fine tuning problem known to physics. The “cosmic coincidence problem” questions the relative coincidence of the orders of magnitude at present of dark matter (DM) and DE energy densities [12]

Objectives

Findings

Discussion

Conclusion