Evidence for a Galactic gamma ray halo

Abstract

We present quantitative statistical evidence for a $\gamma$-ray emission halo surrounding the Galaxy. Maps of the emission are derived. EGRET data were analyzed in a wavelet-based non-parametric hypothesis testing framework, using a model of expected diffuse (Galactic + isotropic) emission as a null hypothesis. The results show a statistically significant large scale halo surrounding the center of the Milky Way as seen from Earth. The halo flux at high latitudes is somewhat smaller than the isotropic gamma-ray flux at the same energy, though of the same order (O(10^(-7)--10^(-6)) ph/cm^2/s/sr above 1 GeV).

arXiv commentFinal version accepted for publication in New Astronomy. Some additional results/discussion included, along with entirely revised figures. 19 pages, 15 figures, AASTeX. Better quality figs (PS and JPEG) are available at http://tigre.ucr.edu/halo/paper.html

References in corpus (6)

• Propagation of cosmic-ray nucleons in the Galaxy
• EGRET Observations of the Extragalactic Gamma Ray Emission
• Baryonic Dark Halos: Machos and Cold Gas?
• On the Density of PBH's in the Galactic Halo
• The Inverse-Compton And Extragalactic Components Of The Diffuse Gamma-Ray Emission
• Gamma Radiation by Neutralino Stars

Cited by in corpus (34)

• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Diffuse continuum gamma rays from the Galaxy
• Cosmological dark matter annihilations into gamma-rays - a closer look
• A new determination of the extragalactic diffuse gamma-ray background from EGRET data
• The Fermi Haze: A Gamma-Ray Counterpart to the Microwave Haze
• Dark Matter: A Primer
• Reionization by Hard Photons: I. X-rays from the First Star Clusters
• The surface brightness of dark matter: unique signatures of neutralino annihilation in the Galactic halo
• Molecules in galaxies
• Supersymmetric Dark Matter and the Extragalactic Gamma Ray Background
• Constraining Strong Baryon-Dark Matter Interactions with Primordial Nucleosynthesis and Cosmic Rays
• The Case for a Low Extragalactic Gamma-ray Background
• Is the dark matter interpretation of the EGRET gamma excess compatible with antiproton measurements?
• Gamma-Ray Background from Neutralino Annihilation in the First Cosmological Objects
• Thermal stability of cold clouds in galaxy halos
• On the Interaction Between Cosmic Rays and Dark Matter Molecular Clouds in the Milky Way. l Basic Considerations
• Indirect search for dark matter: prospects for GLAST
• Particle Annihilation in Cold Dark Matter Micropancakes
• Galactic Gamma Halo by Heavy Neutrino annihilations?
• Is the diffuse gamma background radiation generated by galactic cosmic rays?
• Gamma ray astronomy and baryonic dark matter
• Possible detection of the M31 rotation in WMAP data
• Cosmological gamma ray and neutrino backgrounds due to neutralino dark matter annihilation
• Gamma Rays from Superheavy Relic Particles in the Halo
• The Cloudy Universe
• Dense gas clouds and the Unidentified EGRET sources
• CMB as a possible new tool to study the dark baryons in galaxies
• SUSY dark matter --A collider Physicist's Perspective--
• Virial clouds explaining the observed rotational asymmetry in the galactic halos
• On the Galactic Halos Rotation by Planck Data
• Observation of EGRET Gamma-Ray Sources by an Extensive Air Shower Experiment
• Microlensing by gas filaments
• On the origin of the diffuse gamma-ray background radiation