SIMBAD references

2001ApJ...555...12D - Astrophys. J., 555, 12-22 (2001/July-1)

EGRET observations of Monoceros: diffuse gamma-ray emission in the outer galaxy.

DIGEL S.W., GRENIER I.A., HUNTER S.D., DAME T.M. and THADDEUS P.

Abstract (from CDS):

We present an analysis of the diffuse gamma-ray emission observed toward Monoceros by the Energetic Gamma-Ray Experiment Telescope (EGRET). The region studied, l=210°-250°, b=-15° to +20°, has kinematically well-defined segments of the local and Perseus arms and is one of the best regions for the study of variations of cosmic-ray density across the outer Galaxy. The local gamma-ray emissivity is (1.81±0.17)x10–26 s–1.sr–1 for energies greater than 100 MeV. For energies greater than 300 MeV, the gamma-ray emissivity in Monoceros is consistent with that of other local clouds studied with EGRET, which suggests that the density of GeV cosmic-ray protons does not vary significantly on scales of less than 1 kpc. As with other local clouds studied with EGRET, an excess of emissivity is observed above 1 GeV relative to that predicted from the cosmic-ray spectrum at the Earth. The gamma-ray emissivity is apparently enhanced in the Perseus arm relative to the interarm regions, although to a much lesser degree than predicted by the model of Hunter et al. The molecular mass calibrating ratio, X=N(H2)/WCO, is (1.64±0.31)x1020 cm–2.(K.km.s–1)–1 in the local clouds and is apparently about the same (to within 50%) in Maddalena's cloud. An uncataloged, marginally significant (∼4.5 σ) unidentified point source near (215°.5, 0°.5) with a flux of (1.4±0.5)x10–7 cm–2.s–1 (>100 MeV) is suggested by the data.

Abstract Copyright:

Journal keyword(s): Gamma Rays: Observations - ISM: Molecules - Radio Lines: ISM

Simbad objects: 11

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