Evidence for TeV Gamma-Ray Emission from the Galactic Plane

Abstract

Gamma-ray emission from a narrow band at the Galactic equator has previously been detected up to 30 GeV. We report evidence for a TeV gamma-ray signal from the Galactic plane by Milagro, a large field of view water Cherenkov detector for extensive air showers. An excess with a significance of 4.5 standard deviations has been observed from the region of Galactic longitude between 40 and 100 deg and latitude |b| < 5 deg. Under the assumption of a simple power law spectrum, with no cutoff, in the EGRET-Milagro energy range, the measured integral flux is phi(>3.5TeV) = (6.4 +/- 1.4 +/- 2.1) 10^{-11} cm^{-2}s^{-1} str^{-1}. This flux is consistent with an extrapolation of the EGRET spectrum between 1 and 30 GeV in this Galactic region.

5 pages, 5 figures, revtex4.sty, revised version

References in corpus (4)

• Diffuse Galactic continuum gamma rays. A model compatible with EGRET data and cosmic-ray measurements
• Observation of TeV Gamma Rays from the Crab Nebula with Milagro Using a New Background Rejection Technique
• Tests of Statistical Significance and Background Estimation in Gamma Ray Air Shower Experiments
• Observation by an Air-Shower Array in Tibet of the Multi-TeV Cosmic-Ray Anisotropy due to Terrestrial Orbital Motion Around the Sun

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