The Gamma-Ray-Flux Probability Distribution Function from Galactic Halo Substructure

Abstract

One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and theoretical arguments suggest that the dark matter in the Galactic halo may be clumped into substructure, rather than smoothly distributed. Here we propose the gamma-ray-flux probability distribution function (PDF) as a probe of substructure in the Galactic halo. We calculate this PDF for a phenomenological model of halo substructure and determine the regions of the substructure parameter space in which the PDF may be distinguished from the PDF for a smooth distribution of dark matter. In principle, the PDF allows a statistical detection of substructure, even if individual halos cannot be detected. It may also allow detection of substructure on the smallest microhalo mass scales, $\sim M_{\oplus }$, for weakly-interacting massive particles (WIMPs). Furthermore, it may also provide a method to measure the substructure mass function. However, an analysis that assumes a typical halo substructure model and a conservative estimate of the diffuse background suggests that the substructure PDF may not be detectable in the lifespan of Fermi in the specific case that the WIMP is a neutralino. Nevertheless, for a large range of substructure, WIMP annihilation, and diffuse background models, PDF analysis may provide a clear signature of substructure.

19 pages, 6 figures. Major revision: substructure and annihilation models developed. Accepted for publication in JCAP

References in corpus (63)

• A Universal Density Profile from Hierarchical Clustering
• Particle Dark Matter: Evidence, Candidates and Constraints
• Supersymmetric Dark Matter
• Dark Matter Substructure in Galactic Halos
• Where are the missing galactic satellites?
• The Aquarius Project: the subhalos of galactic halos
• EGRET Observations of the Extragalactic Gamma Ray Emission
• Formation and evolution of galaxy dark matter halos and their substructure
• Dark Matter Halos within Clusters
• Galaxies in N-body simulations: overcoming the overmerging problem
• Dark matter substructure and gamma-ray annihilation in the Milky Way halo
• Earth-mass dark-matter haloes as the first structures in the early Universe
• Dark Matter and Collider Phenomenology of Universal Extra Dimensions
• The first WIMPy halos
• A blueprint for detecting supersymmetric dark matter in the Galactic halo
• Particle Models and the Small-Scale Structure of Dark Matter
• The Small-Scale Power Spectrum of Cold Dark Matter
• The power spectrum of SUSY-CDM on sub-galactic scales
• What mass are the smallest protohalos?
• Effects of cold dark matter decoupling and pair annihilation on cosmological perturbations
• Small-scale clumps in the galactic halo and dark matter annihilation
• Dark matter annihilation in the halo of the Milky Way
• Precise constraints on the dark matter content of Milky Way dwarf galaxies for gamma-ray experiments
• Clumpy Neutralino Dark Matter
• Spectral Gamma-ray Signatures of Cosmological Dark Matter Annihilation
• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• Anisotropy of the cosmic gamma-ray background from dark matter annihilation
• Early supersymmetric cold dark matter substructure
• The surface brightness of dark matter: unique signatures of neutralino annihilation in the Galactic halo
• Dark Matter Annihilation in Substructures Revised
• Dark matter in Draco and the Local Group: Implications for direct detection experiments
• The survival and disruption of CDM micro-haloes: implications for direct and indirect detection experiments
• Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of cosmic gamma-ray background
• The phase-space structure of a dark-matter halo: Implications for dark-matter direct detection experiments
• Galactic Substructure and Direct Detection of Dark Matter
• Dark Matter Subhaloes in Numerical Simulations
• The Detectability of Neutralino Clumps via Atmospheric Cherenkov Telescopes
• Kinetic decoupling of neutralino dark matter
• Destruction of small-scale dark matter clumps in the hierarchical structures and galaxies
• Dynamical and Gravitational Instability of Oscillating-Field Dark Energy and Dark Matter
• Remnants of dark matter clumps
• Conservative Constraints on Dark Matter Annihilation into Gamma Rays
• The observability of gamma-rays from neutralino annihilations in Milky Way substructure
• Revealing dark matter substructure with anisotropies in the diffuse gamma-ray background
• Analytical Approach to Subhaloes Population in Dark Matter Haloes
• Gamma-ray background anisotropy from galactic dark matter substructure
• Anisotropy probe of galactic and extra-galactic Dark Matter annihilations
• Can Dark Matter Annihilation Dominate the Extragalactic Gamma-Ray Background?
• Can Astrophysical Gamma Ray Sources Mimic Dark Matter Annihilation in Galactic Satellites?
• Proper motion of gamma-rays from microhalo sources
• Angular Signatures of Annihilating Dark Matter in the Cosmic Gamma-Ray Background
• Search with EGRET for a Gamma Ray Line from the Galactic Center
• Tidal Destruction of The First Dark Microhalos
• Possible Indications of a Clumpy Dark Matter Halo
• The Signature of Large Scale Structures on the Very High Energy Gamma-Ray Sky
• Gamma-Ray Background from Neutralino Annihilation in the First Cosmological Objects
• Difficulty of detecting minihalos via $\gamma$-rays from dark matter annihilation
• Identifying Dark Matter Annihilation Products In The Diffuse Gamma Ray Background
• Angular Signatures of Dark Matter in the Diffuse Gamma Ray Background
• Can proper motions of dark-matter subhalos be detected?
• Anisotropy of dark matter annihilation with respect to the Galactic plane
• Small scale WIMP physics
• Neutralino annihilation gamma-rays from clumps and the LMC

Cited by in corpus (51)

• A review of indirect searches for particle dark matter
• Galactic Searches for Dark Matter
• Particle Models and the Small-Scale Structure of Dark Matter
• Gamma Ray Signals from Dark Matter: Concepts, Status and Prospects
• A Comprehensive Search for Dark Matter Annihilation in Dwarf Galaxies
• Indication of Gamma-ray Emission from the Newly Discovered Dwarf Galaxy Reticulum II
• The nature of the Diffuse Gamma-Ray Background
• Sensitivity Projections for Dark Matter Searches with the Fermi Large Area Telescope
• Hierarchical Formation of Dark Matter Halos and the Free Streaming Scale
• Galactic Substructure and Dark Matter Annihilation in the Milky Way Halo
• Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT
• Gamma-ray Signal from Earth-mass Dark Matter Microhalos
• Thermal decoupling and the smallest subhalo mass in dark matter models with Sommerfeld-enhanced annihilation rates
• Constraints on the annihilation cross section of dark matter particles from anisotropies in the diffuse gamma-ray background measured with Fermi-LAT
• Gamma-ray background anisotropy from galactic dark matter substructure
• Dark Matter Subhalos In the Fermi First Source Catalog
• Halo Substructure Boosts to the Signatures of Dark Matter Annihilation
• Mapping dark matter in the gamma-ray sky with galaxy catalogs
• Dark matter substructure modelling and sensitivity of the Cherenkov Telescope Array to Galactic dark halos
• Imprint of galaxy clustering in the cosmic gamma-ray background
• Unveiling the Gamma-ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics
• A cross-correlation study of the Fermi-LAT $\gamma$-ray diffuse extragalactic signal
• Distinguishing Dark Matter from Unresolved Point Sources in the Inner Galaxy with Photon Statistics
• Joint power spectrum and voxel intensity distribution forecast on the CO luminosity function with COMAP
• Anisotropies in the gamma-ray sky from millisecond pulsars
• Power spectrum tomography of dark matter annihilation with local galaxy distribution
• Identifying Dark Matter Annihilation Products In The Diffuse Gamma Ray Background
• The high redshift star-formation history from carbon-monoxide intensity maps
• Constraining Dark Matter in Galactic Substructure
• Anisotropies in the Diffuse Gamma-Ray Background from Dark Matter with Fermi LAT: a closer look
• One-point fluctuation analysis of the high-energy neutrino sky
• The detectability of dark matter annihilation with Fermi using the anisotropy energy spectrum of the gamma-ray background
• Canceling out intensity mapping foregrounds
• Constraining Galactic dark matter with gamma-ray pixel counts statistics
• Improving the Sensitivity of Gamma-Ray Telescopes to Dark Matter Annihilation in Dwarf Spheroidal Galaxies
• A Robust Approach to Constraining Dark Matter from Gamma-Ray Data
• Gravitational Nanolensing from Subsolar Mass Dark Matter Halos
• A Compound Poisson Generator approach to Point-Source Inference in Astrophysics
• Gravitational microlensing as a probe for dark matter clumps
• Optimally Mapping Large-Scale Structures with Luminous Sources
• Harnessing the Population Statistics of Subhalos to Search for Annihilating Dark Matter
• Analysis of Fermi-LAT data from Tucana-II: Possible constraints on the Dark Matter models with an intriguing hint of a signal
• The distribution of annihilation luminosities in dark matter substructure
• One-point fluctuation analysis of IceCube neutrino events outlines a significant unassociated isotropic component and constrains the Galactic contribution
• Extracting the unresolved pulsar contribution to the gamma-ray background
• Towards Accurate Modeling of Line-Intensity Mapping One-Point Statistics: Including Extended Profiles
• Constraining Dark Matter Microphysics with the Annihilation Signal from Subhalos
• Can prompt cusps of WIMP dark matter be detected as individual gamma-ray sources?
• Detecting unresolved moving sources in a diffuse background
• Applying Simulation-Based Inference to Spectral and Spatial Information from the Galactic Center Gamma-Ray Excess
• Approximate Bayesian Computation Applied to the Diffuse Gamma-ray Sky