Disentangling cosmic-ray and dark-matter induced gamma-rays in galaxy clusters?

Abstract

Galaxy clusters are among the best targets for indirect dark matter detection in gamma-rays, despite the large astrophysical background expected from these objects. Detection is now within reach of current observatories (Fermi-LAT or Cerenkov telescopes); however, assessing the origin of this signal might be difficult. We investigate whether the behaviour of the number of objects per `flux' bin (logN-logF) and that of the stacked signal could be used as a signature of the dominant process at stake.We use the CLUMPY code to integrate the signal from decaying or annihilating dark matter and cosmic rays along the line of sight. We assume the standard NFW profile for the dark matter density and rely on a parametrised emissivity for the cosmic-ray component. In this context, the consequences of stacking are explored using the MCXC meta-catalogue of galaxy clusters. We find the value of the slope of the logN-logF power law (or the increase of the signal with the number of stacked objects) to be a clear diagnosis to disentangle decaying dark matter from cosmic-ray induced gamma-rays. For dark matter annihilation, depending on the signal boost from the substructures, it is either similar to the cosmic-ray signal (no boost) or similar to the decay case (large boosts). The shift between the brightest object and its followers also depends on the signal origin. For annihilation, this shift and the stacked signal are poorly constrained because of the large uncertainty affecting the boost. We also underline that the angular dependence of the annihilation signal is not universal because of the substructure contribution.

arXiv comment7 pages, 3 figures, minor corrections (to match the A&A accepted version)

References in corpus (60)

• A Universal Density Profile from Hierarchical Clustering
• Profiles of dark haloes: evolution, scatter, and environment
• The Aquarius Project: the subhalos of galactic halos
• Chandra sample of nearby relaxed galaxy clusters: mass, gas fraction, and mass-temperature relation
• Concentrations of Dark Halos from their Assembly Histories
• The universal galaxy cluster pressure profile from a representative sample of nearby systems (REXCESS) and the Y_SZ-M_500 relation
• Halos and galaxies in the standard cosmological model: results from the Bolshoi simulation
• Dark matter halo concentrations in the Wilkinson Microwave Anisotropy Probe year 5 cosmology
• The statistics of LCDM Halo Concentrations
• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• Galaxy cluster X-ray luminosity scaling relations from a representative local sample (REXCESS)
• The MCXC: a Meta-Catalogue of X-ray detected Clusters of galaxies
• The Dependence of Halo Clustering on Halo Formation History, Concentration, and Occupation
• The redshift dependence of the structure of massive LCDM halos
• Accurate universal models for the mass accretion histories and concentrations of dark matter halos
• Very high energy gamma rays from the direction of Sagittarius A*
• Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction
• Mass and Redshift Dependence of Dark Halo Structure
• Multi-frequency analysis of neutralino dark matter annihilations in the Coma cluster
• The structural and scaling properties of nearby galaxy clusters: I - The universal mass profile
• Universal gas density and temperature profile
• The cluster gas mass fraction as a cosmological probe: a revised study
• X-ray gas density profile of clusters of galaxies from the universal dark matter halo
• The mass profile of A1413 observed with XMM-Newton: implications for the M-T relation
• Fermi Discovery of Gamma-Ray Emission from NGC 1275
• Galaxy-cluster gas-density distributions of the Representative XMM-Newton Cluster Structure Survey (REXCESS)
• The Phoenix Project: the Dark Side of Rich Galaxy Clusters
• The Redshift Evolution of LCDM Halo Parameters: Concentration, Spin, and Shape
• Cosmic ray transport in galaxy clusters: implications for radio halos, gamma-ray signatures, and cool core heating
• GeV Gamma-ray Flux Upper Limits from Clusters of Galaxies
• The X-Ray Concentration-Virial Mass Relation
• Anisotropy of the cosmic gamma-ray background from dark matter annihilation
• MAGIC Gamma-ray Telescope Observation of the Perseus Cluster of Galaxies: implications for cosmic rays, dark matter, and NGC1275
• Where will supersymmetric dark matter first be seen?
• Prospects of detecting gamma-ray emission from galaxy clusters: cosmic rays and dark matter annihilations
• Multi-wavelength signals of dark matter annihilations at the Galactic center
• Simulating the gamma-ray emission from galaxy clusters: a universal cosmic ray spectrum and spatial distribution
• A Simple and Accurate Model for Intra-Cluster Gas
• Gas density and X-ray surface brightness profiles of clusters of galaxies from dark matter halo potentials: beyond the isothermal beta model
• Detection of very-high energy γ-ray emission from NGC 1275 by the MAGIC telescopes
• Probing Dark Matter Decay and Annihilation with Fermi LAT Observations of Nearby Galaxy Clusters
• The statistics of the subhalo abundance of dark matter haloes
• Exploring the Energetics of Intracluster Gas with a Simple and Accurate Model
• Fermi-LAT constraints on dark matter annihilation cross section from observations of the Fornax cluster
• Constraints on the multi-TeV particle population in the Coma Galaxy Cluster with H.E.S.S. observations
• CLUMPY: a code for gamma-ray signals from dark matter structures
• Gamma Rays from Clusters and Groups of Galaxies: Cosmic Rays versus Dark Matter
• Implications of Fermi Observations for Hadronic Models of Radio Halos in Clusters of Galaxies
• On the Relevance of Sharp Gamma-Ray Features for Indirect Dark Matter Searches
• Very high energy gamma-ray observations of the galaxy clusters Abell 496 and Abell 85 with H.E.S.S
• TeV Gamma-Ray Observations of the Perseus and Abell 2029 Galaxy Clusters
• Dark matter in the classical dwarf spheroidal galaxies: a robust constraint on the astrophysical factor for gamma-ray flux calculations
• Annihilation vs. Decay: Constraining dark matter properties from a gamma-ray detection
• gamma-rays from annihilating dark matter in galaxy clusters: stacking vs single source analysis
• Decaying dark matter: a stacking analysis of galaxy clusters to improve on current limits
• The polytropic approximation and X-ray scaling relations: constraints on gas and dark matter profiles for galaxy groups and clusters
• Multi-messenger constraints on the annihilating dark matter interpretation of the positron excess
• CANGAROO-III search for TeV Gamma-rays from two clusters of galaxies
• Disentangling the gamma-ray emission of NGC1275 and that of the Perseus cluster
• Determining all gas properties in galaxy clusters from the dark matter distribution alone

Cited by in corpus (10)

• Dark matter annihilation and decay in dwarf spheroidal galaxies: The classical and ultrafaint dSphs
• Spherical Jeans analysis for dark matter indirect detection in dwarf spheroidal galaxies - Impact of physical parameters and triaxiality
• CLUMPY: Jeans analysis, $\gamma$-ray and neutrino fluxes from dark matter (sub-)structures
• CLUMPY v3: $\gamma$-ray and $\nu$ signals from dark matter at all scales
• Dark matter substructure modelling and sensitivity of the Cherenkov Telescope Array to Galactic dark halos
• Dark Matter Indirect Signatures
• $\gamma$-ray and $\nu$ searches for dark matter subhalos in the Milky Way with a baryonic potential
• Neutron star mass in dark matter clumps
• Classification of gamma-ray targets for velocity-dependent and subhalo-boosted dark-matter annihilation
• Towards a Bullet-proof test for indirect signals of dark matter