Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Constraints on neutrino -- dark matter interactions from cosmic microwave background and large scale structure data

P. Serra, F. Zalamea, A. Cooray, G. Mangano, A. Melchiorri

TL;DR

Problem: investigate non-standard interactions between neutrinos and dark matter using the latest CMB and large-scale-structure data. Approach: parameterize the interaction with an opacity P that scales with the scale factor, and constrain the interacting dark-matter fraction and P via a full Monte Carlo Markov Chain analysis using WMAP5 and SDSS. Findings: the coupling leads to diffusion-damped oscillations in the matter power spectrum and small modifications to the CMB acoustic peaks; the resulting bounds show that stronger couplings are allowed only for small interacting fractions, while standard cosmology is recovered when that fraction is negligible. Significance: these cosmological constraints inform model-building for neutrino-dark-matter couplings and help delineate the viable parameter space for mediator and dark-matter masses.

Abstract

We update a previous investigation of cosmological effects of a non-standard interaction between neutrinos and dark matter. Parameterizing the elastic-scattering cross section between the two species as a function of the temperature of the universe, the resulting neutrino-dark matter fluid has a non-zero pressure, which determines diffusion-damped oscillations in the matter power spectrum similar to the acoustic oscillations generated by the photon-baryon fluid. Using cosmic microwave background data in combination with large scale structure experiment results, we then put constraints on the fraction of the interacting dark matter component as well as on the corresponding opacity.

Constraints on neutrino -- dark matter interactions from cosmic microwave background and large scale structure data

TL;DR

Problem: investigate non-standard interactions between neutrinos and dark matter using the latest CMB and large-scale-structure data. Approach: parameterize the interaction with an opacity P that scales with the scale factor, and constrain the interacting dark-matter fraction and P via a full Monte Carlo Markov Chain analysis using WMAP5 and SDSS. Findings: the coupling leads to diffusion-damped oscillations in the matter power spectrum and small modifications to the CMB acoustic peaks; the resulting bounds show that stronger couplings are allowed only for small interacting fractions, while standard cosmology is recovered when that fraction is negligible. Significance: these cosmological constraints inform model-building for neutrino-dark-matter couplings and help delineate the viable parameter space for mediator and dark-matter masses.

Abstract

We update a previous investigation of cosmological effects of a non-standard interaction between neutrinos and dark matter. Parameterizing the elastic-scattering cross section between the two species as a function of the temperature of the universe, the resulting neutrino-dark matter fluid has a non-zero pressure, which determines diffusion-damped oscillations in the matter power spectrum similar to the acoustic oscillations generated by the photon-baryon fluid. Using cosmic microwave background data in combination with large scale structure experiment results, we then put constraints on the fraction of the interacting dark matter component as well as on the corresponding opacity.

Paper Structure

This paper contains 4 sections, 10 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Neutrino-dark-matter scatterings
  3. Analysis
  4. Conclusions

Figures (2)

  • Figure 1: A perturbation of interacting dark matter (red line) of wavenumber $k=0.81\,h\,$Mpc$^{-1}$ is plotted against a perturbation of non-interacting dark matter (black dotted line) in the upper panel. The effects of this interaction are clearly seen in the angular power spectum of the CMB (middle panel) and on the matter power spectum (lower panel). We have chosen a very large value of Q to magnify the effect on the main cosmological observables.
  • Figure 2: Constraints in the cross section parameter $Q$ versus $\Omega_X h^2$ plane from the combination of WMAP and SDSS data. Large values for the neutrino-dark matter interaction are always compatible with the standard picure, provided that the energy content of the interacting dark matter is small enough.