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 -1 sr -1 above 1 GeV).
- Publication:
-
New Astronomy
- Pub Date:
- November 1998
- DOI:
- 10.1016/S1384-1076(98)00024-4
- arXiv:
- arXiv:astro-ph/9803237
- Bibcode:
- 1998NewA....3..539D
- Keywords:
-
- Astrophysics
- E-Print:
- Final 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