Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Probing the nature of dark matter with Cosmic X-rays: Constraints from "Dark blobs" and grating spectra of galaxy clusters

Signe Riemer-Sorensen, Kristian Pedersen, Steen H. Hansen, Haakon Dahle

TL;DR

This work targets the particle nature of dark matter by leveraging high-resolution X-ray observations of DM-dominated systems. By applying a conservative slice method to both the Abell 1835 grating data and the Abell 520 dark-matter blob, the authors derive robust upper limits on radiative two-body decays, translating these into constraints on sterile-neutrino parameters. The analysis yields strong bounds that push $m_s$ to below about $10$ keV and restricts $\sin^2(2\theta)$ to the $\lesssim 10^{-6}$ range in the low-mass regime, though other production mechanisms for sterile neutrinos may still be viable. The results demonstrate the power of precise X-ray spectroscopy in probing dark-matter candidates and outline clear paths to even tighter constraints with improved field-of-view optimization and spectral resolution.

Abstract

Gravitational lensing observations of galaxy clusters have identified dark matter ``blobs'' with remarkably low baryonic content. We use such a system to probe the particle nature of dark matter with X-ray observations. We also study high resolution X-ray grating spectra of a cluster of galaxies. From these grating spectra we improve the conservative constraints on a particular dark matter candidate, the sterile neutrino, by more than one order of magnitude. Based on these conservative constraints obtained from Cosmic X-ray observations alone, the low mass (m_s < 10keV) and low mixing angle (sin^2(2θ) 10^{-6}) sterile neutrino is still a viable dark matter candidate.

Probing the nature of dark matter with Cosmic X-rays: Constraints from "Dark blobs" and grating spectra of galaxy clusters

TL;DR

This work targets the particle nature of dark matter by leveraging high-resolution X-ray observations of DM-dominated systems. By applying a conservative slice method to both the Abell 1835 grating data and the Abell 520 dark-matter blob, the authors derive robust upper limits on radiative two-body decays, translating these into constraints on sterile-neutrino parameters. The analysis yields strong bounds that push to below about keV and restricts to the range in the low-mass regime, though other production mechanisms for sterile neutrinos may still be viable. The results demonstrate the power of precise X-ray spectroscopy in probing dark-matter candidates and outline clear paths to even tighter constraints with improved field-of-view optimization and spectral resolution.

Abstract

Gravitational lensing observations of galaxy clusters have identified dark matter ``blobs'' with remarkably low baryonic content. We use such a system to probe the particle nature of dark matter with X-ray observations. We also study high resolution X-ray grating spectra of a cluster of galaxies. From these grating spectra we improve the conservative constraints on a particular dark matter candidate, the sterile neutrino, by more than one order of magnitude. Based on these conservative constraints obtained from Cosmic X-ray observations alone, the low mass (m_s < 10keV) and low mixing angle (sin^2(2θ) 10^{-6}) sterile neutrino is still a viable dark matter candidate.

Paper Structure

This paper contains 7 sections, 6 equations, 4 figures.

Table of Contents

  1. Introduction
  2. X-ray Data Analysis
  3. Grating Observations of The Galaxy Cluster Abell 1835
  4. The Dark Matter Blob in the Galaxy Cluster Abell 520
  5. Decay Rate
  6. Constraining Mass and Mixing Angle
  7. Conclusions

Figures (4)

  • Figure 1: (Color online) Abell 520 observed in X-rays (0.3-10.0 keV, blue color) with Chandra with the gravitational potential from weak lensing overlaid (green contours). The dark matter blob in the red circle has very low X-ray emission from baryons.
  • Figure 2: (Color online) The upper limit on the radiative two-body decay rate obtained from the dark matter blob of Abell 520 (dashed) and the grating spectra of Abell 1835 (solid) shown together with the Milky Way halo constraint blanksky (dot-dashed).
  • Figure 3: (Color online) The Abell 1835 grating spectrum upper limit on the decay rate and its approximate analytical expression given by of eq. \ref{['eqn:analytical']}.
  • Figure 4: (Color online) The observational constraints from the grating spectrum of Abell 1835 (red) and the dark matter blob of A520 (orange) together with the Tremaine-Gunn limit (black, tremaine) and earlier X-ray constraints (yellow, boyarsky:2005aboyarsky:2006aboyarsky:2006bwatson:2006blanksky).