Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Restrictions on parameters of sterile neutrino dark matter from observations of galaxy clusters

Alexey Boyarsky, Andrey Neronov, Oleg Ruchayskiy, Mikhail Shaposhnikov

TL;DR

The study investigates keV-scale sterile neutrino dark matter by searching for the radiative decay line at energy $E = m_s/2$ in X-ray spectra of the Coma and Virgo galaxy clusters. By combining total-flux and spectral-line (statistical) analyses and exploiting peripheral cluster regions where the DM signal is less outshined by hot gas, the authors derive constraints in the $(m_s,\sin^2(2\theta))$ parameter space, with Coma periphery providing the strongest robust bound and Virgo becoming competitive at higher masses ($m_s\gtrsim 14$ keV). The statistical-line analysis strengthens limits by factors of about 2–4 over prior X-ray background bounds in the 2–10 keV range, and the results help reconcile discrepancies with earlier claims by highlighting the importance of realistic flux estimates from cluster cores. Overall, the work refines the viable sterile-neutrino DM parameter space and demonstrates the value of peripheral-cluster spectroscopy for indirect DM searches.

Abstract

We find restrictions on the mass and mixing angle of the dark matter sterile neutrinos using X-ray observations of Coma and Virgo galaxy clusters.

Restrictions on parameters of sterile neutrino dark matter from observations of galaxy clusters

TL;DR

The study investigates keV-scale sterile neutrino dark matter by searching for the radiative decay line at energy in X-ray spectra of the Coma and Virgo galaxy clusters. By combining total-flux and spectral-line (statistical) analyses and exploiting peripheral cluster regions where the DM signal is less outshined by hot gas, the authors derive constraints in the parameter space, with Coma periphery providing the strongest robust bound and Virgo becoming competitive at higher masses ( keV). The statistical-line analysis strengthens limits by factors of about 2–4 over prior X-ray background bounds in the 2–10 keV range, and the results help reconcile discrepancies with earlier claims by highlighting the importance of realistic flux estimates from cluster cores. Overall, the work refines the viable sterile-neutrino DM parameter space and demonstrates the value of peripheral-cluster spectroscopy for indirect DM searches.

Abstract

We find restrictions on the mass and mixing angle of the dark matter sterile neutrinos using X-ray observations of Coma and Virgo galaxy clusters.

Paper Structure

This paper contains 16 sections, 22 equations, 10 figures.

Table of Contents

  1. Introduction
  2. DM decay line vs. thermal bremsstrahlung emission.
  3. Data Analysis
  4. "Total flux" restrictions.
  5. Analysis for Coma cluster
  6. Coma periphery
  7. Analysis for Virgo cluster
  8. Virgo periphery
  9. Statistical analysis of the XMM data
  10. Bounds from statistical analysis of the Coma cluster observations.
  11. Bounds from statistical analysis of the of Virgo cluster.
  12. Results
  13. Discussion.
  14. Simple model for the X-ray spectrum of the core of Coma cluster.
  15. Simple model for the X-ray spectrum of the core of Virgo cluster.
  16. ...and 1 more sections

Figures (10)

  • Figure 1: Exclusion plot from the total flux restriction from the circular region with radius $700"$ in the center of Coma cluster. The straight green lines represent $\sin^2(2\theta) m_s^5 = \mathrm{const}$ lines, corresponding to the total flux at energies 1 keV and 10 keV (in the 200 eV energy bin).
  • Figure 2: Exclusion plot based on the restrictions derived from a total flux from Coma 3 peripheral observation (red solid line) as compared with Coma center (green line, identical to the red curve on Fig. \ref{['fig:coma-center-total-flux']}). Thinner blue lines represent $m_s^5\sin^2(2\theta) =\mathrm{const}$ with normalization corresponding to fluxes at 1 keV and 7 keV.
  • Figure 3: Comparison between Coma center (red curve) and Coma 3 (green curve) fluxes (per 200 eV energy bin).
  • Figure 4: Restrictions based on the total flux from the circle with the radius $11'$ with the center at M87 (red line). Green line represents the data for Coma periphery -- same as on Fig. \ref{['fig:coma3-total-flux']}. Blue line -- restriction (\ref{['xrbbound']}) from Boyarsky:05.
  • Figure 5: Red line: exclusion plot based on statistical analysis from Coma center observation (circular region of the radius $700"$ around the center of the cluster). Green line -- restriction based on the total flux from the same region (curve from Fig. \ref{['fig:coma-center-total-flux']}).
  • ...and 5 more figures