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Signature of the interaction between dark energy and dark matter in observations

Elcio Abdalla, L. Raul Abramo, Jose C. C. de Souza

TL;DR

This work tests whether a coupling between dark energy and dark matter can affect galaxy cluster dynamics by modifying the Layser–Irvine virial relation. It analyzes nearly 100 clusters with virial, X-ray, and weak-lensing mass estimates and parameterizes deviations with a single coupling parameter $\bar{\zeta}$. The analysis yields a nonzero positive coupling, $\bar{\zeta} \approx 0.14 \pm 0.10$ in a conservative treatment, suggesting energy transfer from dark energy to dark matter. The result is broadly consistent with other constraints that permit small positive couplings and has implications for structure formation and DM density evolution, motivating further observational and theoretical work.

Abstract

We investigate the effect of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. This effect is computed through the Layser-Irvine equation, which describes how an astrophysical system reaches virial equilibrium and was modified to include the dark interactions. Using observational data from almost 100 purportedly relaxed galaxy clusters we put constraints on the strength of the couplings in the dark sector. We compare our results with those from other observations and find that a positive (in the sense of energy flow from dark energy to dark matter) non vanishing interaction is consistent with the data within several standard deviations.

Signature of the interaction between dark energy and dark matter in observations

TL;DR

This work tests whether a coupling between dark energy and dark matter can affect galaxy cluster dynamics by modifying the Layser–Irvine virial relation. It analyzes nearly 100 clusters with virial, X-ray, and weak-lensing mass estimates and parameterizes deviations with a single coupling parameter . The analysis yields a nonzero positive coupling, in a conservative treatment, suggesting energy transfer from dark energy to dark matter. The result is broadly consistent with other constraints that permit small positive couplings and has implications for structure formation and DM density evolution, motivating further observational and theoretical work.

Abstract

We investigate the effect of an interaction between dark energy and dark matter upon the dynamics of galaxy clusters. This effect is computed through the Layser-Irvine equation, which describes how an astrophysical system reaches virial equilibrium and was modified to include the dark interactions. Using observational data from almost 100 purportedly relaxed galaxy clusters we put constraints on the strength of the couplings in the dark sector. We compare our results with those from other observations and find that a positive (in the sense of energy flow from dark energy to dark matter) non vanishing interaction is consistent with the data within several standard deviations.

Paper Structure

This paper contains 5 sections, 20 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Phenomenology of Coupled Dark Energy And Dark Matter Models
  3. Mass estimation and limits on the coupling
  4. Comparison with previous results
  5. Conclusions

Figures (3)

  • Figure 1: Probability density function (p.d.f.) for $\bar{\zeta}$ obtained with all available cluster masses. The result points to $\bar{\zeta} = 0.14\pm 0.01$, that is, 14 standard deviations from the null result.
  • Figure 2: P.d.f's concerning the cluster data divided in three sets, in increasing order of the dispersion velocity (up to 600 km/s, from 600 to 1000 km/s, and above 1000 km/s.) The data are compatible with one another and the results point to essentially the same values of $\bar{\zeta}$, all at least three standard deviations from the null result.
  • Figure 3: P.d.f's concerning the cluster data divided in two sets, in increasing order of the redshift (below and above $z=0.05$). The data are compatible with one another and the results point to compatible values of $\bar{\zeta}$, at several standard deviations from a vanishing result. However, in the absence of weak lensing results the results point to a considerably higher value of the coupling compared with the previous ones.