Abstract COS-B gamma-ray observations are compared with large-scale HI and CO surveys in different regions of the sky to derive information on the cosmic-ray density distribution throughout the Galaxy and/or a calibration of the ratio between H2 column density and integrated CO line intensity [ N(H 2 ) W co ]. In the region of the large complex of interstellar clouds in Orion and Monoceros the observed gamma-ray emission can be explained in terms of interactions between cosmic rays distributed uniformly with the local density in this region, and the interstellar gas. In the outer galaxy a steep negative gradient of the emissivity for the 70–150 MeV energy range is found, interpreted as a steep gradient in the cosmic-ray electron density. The emissivity for the 300–5000 MeV range is found to be approximately constant (within 20%) and equal to the local value out to large (∼20 kpc) galacto-centric distances, interpreted as a near constancy of the nuclear component. Results sofar available for the inner galaxy indicate that this trend, a stronger gradient in the electron distribution compared to that of the nuclei, can be extrapolated into the Galaxy. Calibration of the ratio N(H 2 ) W co in the Orion, Monoceros region and in the first galactic quadrant give consistent values in the range (2.5–3) 1020 molecules cm−2 K−1 km−1 s. The galactic centre region is found to be an anomaly: (i) the density of cosmic-ray nuclei with energies of ∼1 GeV is anomalously small relative to the local value, or (ii) perhaps these cosmic rays do not efficiently penetrate the molecular clouds in the central region of the Galaxy (contrary to the case of Orion) or (iii) the N(H 2 ) W co ratio is anomalously low.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    The galactic distribution of cosmic-ray particles


    Contributors:

    Published in:

    Advances in Space Research ; 4 , 2-3 ; 393-404


    Publication date :

    1984-01-01


    Size :

    12 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



    Galactic cosmic rays

    Hayakawa, S. | Elsevier | 1984


    Radial distribution of galactic cosmic rays at solar maximum

    Morales-Olivares, O.G. | Online Contents | 2012


    Radial distribution of galactic cosmic rays at solar maximum

    Morales-Olivares, O.G. / Caballero-Lopez, R.A. | Elsevier | 2012


    An analytical model, describing dynamics of galactic cosmic ray heavy particles

    Nymmik, R.A. / Panasyuk, M.I. / Pervaya, T.I. et al. | Elsevier | 1994