THE FERMI GAMMA-RAY HAZE FROM DARK MATTER ANNIHILATIONS AND ANISOTROPIC DIFFUSION

Journal Article · Tue Nov 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/741/1/25; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587300

Dobler, Gregory ^[1]; Cholis, Ilias ^[2]; Weiner, Neal ^[3]

---

1. Kavli Institute for Theoretical Physics, University of California, Santa Barbara Kohn Hall, Santa Barbara, CA 93106 (United States)
2. Astrophysics Sector, La Scuola Internazionale Superiore di Studi Avanzati and Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, via Bonomea 265, 34136 Trieste (Italy)
3. Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

Recent full-sky maps of the Galaxy from the Fermi Gamma-Ray Space Telescope have revealed a diffuse component of emission toward the Galactic center and extending up to roughly {+-}50{sup 0} in latitude. This Fermi 'haze' is the inverse Compton emission generated by the same electrons that generate the microwave synchrotron haze at Wilkinson Microwave Anisotropy Probe wavelengths. The gamma-ray haze has two distinct characteristics: the spectrum is significantly harder than emission elsewhere in the Galaxy and the morphology is elongated in latitude with respect to longitude with an axis ratio of {approx}2. If these electrons are generated through annihilations of dark matter (DM) particles in the Galactic halo, this morphology is difficult to realize with a standard spherical halo and isotropic cosmic-ray (CR) diffusion. However, we show that anisotropic diffusion along ordered magnetic field lines toward the center of the Galaxy coupled with a prolate DM halo can easily yield the required morphology without making unrealistic assumptions about diffusion parameters. Furthermore, a Sommerfeld enhancement to the self-annihilation cross-section of {approx}30 yields a good fit to the morphology, amplitude, and spectrum of both the gamma-ray and microwave haze. The model is also consistent with local CR measurements as well as cosmic microwave background constraints.

• OSTI ID: 21587300
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 741; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
ANNIHILATION
BOSONS
COSMIC PHOTONS
COSMIC RADIATION
DIFFUSION
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
FERMIONS
GALAXIES
GAMMA RADIATION
INTERACTIONS
IONIZING RADIATIONS
LEPTONS
MASSLESS PARTICLES
MATTER
MICROWAVE RADIATION
MORPHOLOGY
NONLUMINOUS MATTER
PARTICLE INTERACTIONS
PHOTONS
RADIATIONS
RELICT RADIATION