298 articles – 2327 Notices  [english version]
 HAL : in2p3-00429043, version 1
 arXiv : 0908.1171
 Astrophysical Journal 703 (2009) 1249-1256
 Fermi LAT Observation of Diffuse Gamma-Rays Produced Through Interactions between Local Interstellar Matter and High Energy Cosmic Rays
 (01/10/2009)
 Observations by the Large Area Telescope (LAT) on the \textit{Fermi} mission of diffuse $\gamma$-rays in a mid-latitude region in the third quadrant (Galactic longitude $l$ from $200\arcdeg$ to $260\arcdeg$ and latitude $| b |$ from $22\arcdeg$ to $60\arcdeg$) are reported. The region contains no known large molecular cloud and most of the atomic hydrogen is within 1 kpc of the solar system. The contributions of $\gamma$-ray point sources and inverse Compton scattering are estimated and subtracted. The residual $\gamma$-ray intensity exhibits a linear correlation with the atomic gas column density in energy from 100 MeV to 10 GeV. The measured integrated $\gamma$-ray emissivity is $(1.63 \pm 0.05) \times 10^{-26} {\rm photons s^{-1} sr^{-1} H\mathchar-atom^{-1}}$ and $(0.66 \pm 0.02) \times 10^{-26} {\rm photons s^{-1} sr^{-1} H\mathchar-atom^{-1}}$ above 100 MeV and above 300 MeV, respectively, with additional systematic error of $\sim 10%$. The differential emissivity in 100 MeV--10 GeV agrees with calculations based on cosmic ray spectra consistent with those directly measured, at the 10% level. The results obtained indicate that cosmic ray nuclei spectra within 1 kpc from the solar system in regions studied are close to the local interstellar spectra inferred from direct measurements at the Earth within $\sim 10%$.
 Thème(s) : Physique/Astrophysique/Phénomènes cosmiques de haute energiePlanète et Univers/Astrophysique/Phénomènes cosmiques de haute energie
 Mot(s)-clé(s) : cosmic rays – diffuse radiation – gamma rays: observations
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0908.1171
 in2p3-00429043, version 1 http://hal.in2p3.fr/in2p3-00429043 oai:hal.in2p3.fr:in2p3-00429043 Contributeur : Virginie Mas <> Déposé pour le compte de : David Smith <> Soumis le : Vendredi 30 Octobre 2009, 15:15:37 Dernière modification le : Vendredi 30 Octobre 2009, 15:42:25