A Possible Approach to Three‐dimensional Cosmic‐Ray Propagation in the Galaxy. III. Unstable Nuclei

The topic of this presentation is the origin and dynamical behavior of the magnetic field and cosmic-ray gas in the disk of the Galaxy. In the space available I can do no more than mention the ideas that have been developed, with but little explanation and discussion. To make up for this inadequacy I have tried to give a complete list of references in the written text, so that the interested reader can pursue the points in depth (in particular see the review articles Parker, 1968a, 1969a, 1970). My purpose here is twofold, to outline for you the calculations and ideas that have developed thus far, and to indicate the uncertainties that remain. The basic ideas are sound, I think, but, when we come to the details, there are so many theoretical alternatives that need yet to be explored and so much that is not yet made clear by observations.

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Where Does the Galaxy End?

Symposium - International Astronomical Union ◽

10.1017/s0074180900230568 ◽

1996 ◽

Vol 169 ◽

pp. 669-680

Author(s):

F.D.A. Hartwick

Keyword(s):

Spatial Distribution ◽

Globular Clusters ◽

Semimajor Axis ◽

Three Dimensional ◽

Minor Axis ◽

Spatial Extension ◽

The Galaxy ◽

Nested Hierarchy ◽

Satellite Galaxies ◽

Dimensional Surface

The spatial distribution of the outlying satellites of the Galaxy has been determined by fitting a three dimensional surface to the positions of 10 companion galaxies and 13 distant globular clusters. Both groups show a highly flattened distribution whose minor axes are aligned to within ∼ 5°. The combined group of 23 objects shows a triaxial distribution with semimajor axis extending ∼ 400 kpc. The minor axis is inclined at ∼ 76° to the Galactic poles. There is a suggestion of a nested hierarchy consisting of satellite galaxies, globular clusters, and distant halo field stars, in order of decreasing spatial extension.

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Inferring the three-dimensional distribution of dust in the Galaxy with a non-parametric method

Astronomy and Astrophysics ◽

10.1051/0004-6361/201628885 ◽

2017 ◽

Vol 598 ◽

pp. A125 ◽

Cited By ~ 17

Author(s):

S. Rezaei Kh. ◽

C. A. L. Bailer-Jones ◽

R. J. Hanson ◽

M. Fouesneau

Keyword(s):

Parametric Method ◽

Three Dimensional ◽

The Galaxy ◽

Dimensional Distribution ◽

Non Parametric

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Distribution of arrival times in cosmic ray showers

Advances in Applied Probability ◽

10.2307/1426654 ◽

1978 ◽

Vol 10 (4) ◽

pp. 730-735

Author(s):

H. S. Green

Keyword(s):

Cosmic Radiation ◽

Three Dimensional ◽

Stochastic Theory ◽

Cosmic Ray ◽

Time Of Arrival ◽

Air Showers ◽

Actual Distribution ◽

Arrival Times ◽

Primary Particles ◽

Theoretical Analyses

The theoretical analyses of the extensive air showers developing from the cosmic radiation has its origins in the work of Carlson and Oppenheimer (1937) and Bhabha and Heitler (1937), at a time when it was thought that such showers were initiated by electrons. The realization that protons and other nuclei were the primary particles led to a reformulation of the theory by Heitler and Janossy (1949), Messel and Green (1952) and others, in which the production of energetic pions and the three-dimensional development of air showers were accounted for. But as the soft (electromagnetic) component of the cosmic radiation is the most prominent feature of air showers at sea level, there has been a sustained interest in the theory of this component. Most of the more recent work, such as that by Butcher and Messel (1960) and Thielheim and Zöllner (1972) has relied on computer simulation; but this method has disadvantages in terms of accuracy and presentation of results, especially where a simultaneous analysis of the development of air showers in terms of several physical variables is required. This is so for instance when the time of arrival is one of the variables. Moyal (1956) played an important part in the analytical formulation of a stochastic theory of cosmic ray showers, with time as an explicit variable, and it is essentially this approach which will be adopted in the following. The actual distribution of arrival times is cosmic ray showers, for which results are obtained, is of current experimental interest (McDonald, Clay and Prescott (1977)).

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