Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

The Abell Cluster A586 and the Detection of the Equivalence Principle

O. Bertolami, F. Gil Pedro, M. Le Delliou

TL;DR

The paper investigates whether interactions in the dark sector can induce an Equivalence Principle (EP) violation in a cosmological setting, using Abell A586 as a diagnostic of DE–DM coupling. It frames a two-part EP-violation typology and connects a DE–DM interaction to an effective, time-varying gravitational coupling for dark matter, comparing cluster-scale signals with cosmological constraints from CMB, SNIa, and BAO. The authors argue that varying-coupling DE–DM models can be compatible with existing data and that the A586 signal can be interpreted as energy transfer from DM to DE affecting DM gravity, a view that aligns with some dark-sector simulations while highlighting tensions in other contexts. Overall, the work supports the plausibility of a nontrivial, interacting dark sector and emphasizes the need for targeted simulations and multi-system tests to probe EP validity in the dark sector.

Abstract

We discuss the current bounds on the Equivalence Principle, in particular from structure formation and, reexamine in this context, the recent claim on the evidence of the interaction between dark matter and dark energy in the Abell Cluster A586 and the ensued violation of the Equivalence Principle.

The Abell Cluster A586 and the Detection of the Equivalence Principle

TL;DR

The paper investigates whether interactions in the dark sector can induce an Equivalence Principle (EP) violation in a cosmological setting, using Abell A586 as a diagnostic of DE–DM coupling. It frames a two-part EP-violation typology and connects a DE–DM interaction to an effective, time-varying gravitational coupling for dark matter, comparing cluster-scale signals with cosmological constraints from CMB, SNIa, and BAO. The authors argue that varying-coupling DE–DM models can be compatible with existing data and that the A586 signal can be interpreted as energy transfer from DM to DE affecting DM gravity, a view that aligns with some dark-sector simulations while highlighting tensions in other contexts. Overall, the work supports the plausibility of a nontrivial, interacting dark sector and emphasizes the need for targeted simulations and multi-system tests to probe EP validity in the dark sector.

Abstract

We discuss the current bounds on the Equivalence Principle, in particular from structure formation and, reexamine in this context, the recent claim on the evidence of the interaction between dark matter and dark energy in the Abell Cluster A586 and the ensued violation of the Equivalence Principle.

Paper Structure

This paper contains 7 sections, 5 equations, 2 figures.

Table of Contents

  1. Introduction
  2. An EP Violation Typology
  3. Baryonic composition dependent violation of the EP
  4. Dark sector violation of the EP
  5. DE-DM Interaction and EP Violation
  6. EP Violation, Free Fall and Structure Formation
  7. Discussion and Conclusions

Figures (2)

  • Figure 1: Superimposition of the probability contours for the interacting DE-DM model in the ($\omega_{X}$,$\xi$) plane (denoted as ($\omega_{DE_{0}}$,$\eta$) in Bertolami et al.Berto07), marginalized over $\Omega_{DE_{0}}$ in Guo et al.Guo07 study of CMB, SNIa and BAO (2.66$<\xi<$4.05 at 95% C.L.) with the extended results of Bertolami et al.Berto07 based on the study of A586 cluster. The $\xi=-3\omega_{X}$ dashed line corresponds to uncoupled models. The result of Bertolami et al.Berto07 is set at $\omega_{X}=-1$ and error bars are shown. The thick lines corresponds to their extension to varying $\omega_{X}$.
  • Figure 2: Evolution with redshift of the ratio of the gravitational coupling for DM and baryons falling on a DM halo, using the varying coupling model discussed in Bertolami et al.Berto07, as compared with the simulation of Kesden and Kamionkowski KesdenKamion06.