Space Science Division, Naval Research Laboratory, Washington, DC 20375, USA.
Phys Rev Lett. 2009 Dec 18;103(25):251101. doi: 10.1103/PhysRevLett.103.251101. Epub 2009 Dec 16.
The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.
弥漫银河伽马射线发射是由宇宙射线（CRs）与星际气体和辐射场相互作用产生的。康普顿伽马射线观测站（Compton Gamma-Ray Observatory）上的能谱伽马射线实验望远镜（EGRET）仪器的测量结果表明，相对于与直接测量的 CR 谱一致的弥漫银河伽马射线发射模型，伽马射线发射过量，>或大约等于 1GeV（所谓的“EGRET GeV 过剩”）。费米伽马射线太空望远镜（Fermi Gamma-Ray Space Telescope）上的大面积望远镜（LAT）仪器与 EGRET 相比，具有更高的灵敏度和分辨率，可测量弥漫伽马射线发射。我们报告了 LAT 在 100MeV 至 10GeV 的能量和 10 度<或=|b|<或=20 度的银河纬度上的测量结果。天空这一区域的 LAT 谱很好地被一个与局部 CR 谱一致、与 EGRET GeV 过剩不一致的弥漫银河伽马射线发射模型所再现。
