gamma-rays from annihilating dark matter in galaxy clusters: stacking vs single source analysis
arXiv:1203.1165 · doi:10.1111/j.1365-2966.2012.21484.x
Abstract
Clusters of galaxies are potentially important targets for indirect searches for dark matter annihilation. Here we reassess the detection prospects for annihilation in massive halos, based on a statistical investigation of 1743 clusters in the new Meta-Catalog of X-ray Clusters. We derive a new limit for the extra-galactic dark matter annihilation background of at least 20% of that originating from the Galaxy for an integration angle of 0.1 deg. The number of clusters scales as a power law with their brightness, suggesting that stacking may provide a significant improvement over a single target analysis. The mean angle containing 80% of the dark-matter signal for the sample is ~0.15 deg, indicating that instruments with this angular resolution or better would be optimal for a cluster annihilation search based on stacking. A detailed study based on the Fermi-LAT performance and position-dependent background, suggests that stacking may result in a factor ~2 improvement in sensitivity, depending on the source selection criteria. Based on the expected performance of CTA, we find no improvement with stacking, due to the requirement for pointed observations. We note that several potentially important targets: Opiuchius, A2199, A3627 (Norma) and CIZAJ1324.7-5736 may be disfavoured due to a poor contrast with respect to the Galactic dark-matter signal. The use of the homogenised MCXC meta-catalogue provides a robust ranking of the targets, although the absolute value of their signal depends on the exact dark matter substructure content. For conservative assumptions, we find that galaxy clusters (with or without stacking) can probe <sigma v> down to 1e-25-1e-24 cm3/s for dark matter masses in the range 10 GeV-100 GeV. For more favourable substructure configurations, <sigma v>~1e-26 cm3/s may be reached.
11 pages, 6+2(new) figures, impact of substructures discussed in new Sec 3.4 (matches accepted MNRAS version). Supplementary file available at http://lpsc.in2p3.fr/clumpy/downloads.html
References in corpus (18)
- Heating Hot Atmospheres with Active Galactic Nuclei
- Shocks and cold fronts in galaxy clusters
- Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
- The redshift dependence of the structure of massive LCDM halos
- Combining Strong and Weak Gravitational Lensing in Abell 1689
- Statistics of X-ray observables for the cooling-core and non-cooling core galaxy clusters
- What mass are the smallest protohalos?
- Total mass biases in X-ray galaxy clusters
- Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope
- Precise constraints on the dark matter content of Milky Way dwarf galaxies for gamma-ray experiments
- The X-Ray Concentration-Virial Mass Relation
- The statistics of the subhalo abundance of dark matter haloes
- Fitting formulae for photon spectra from WIMP annihilation
- Photon spectra from WIMP annihilation
- Gamma Rays from Clusters and Groups of Galaxies: Cosmic Rays versus Dark Matter
- Dark matter in the classical dwarf spheroidal galaxies: a robust constraint on the astrophysical factor for gamma-ray flux calculations
- Decaying dark matter: a stacking analysis of galaxy clusters to improve on current limits
- Subhaloes in Scale-Free Cosmologies