A Science Strategy for Space Physics (1995) / Chapter Skim
Currently Skimming:
A Science Strategy for Space Physics: Chapter 5
A Science Strategy for Space Physics: Chapter 5
Pages 82-90
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 82... ...
The study REPORT MENU of these particles provides a vital bridge between space plasma physics using in situ NOTICE measurements and remote sensing of astrophysical objects where cosmic rays may have MEMBERSHIP important dynamical consequences. Studies of point sources of gamma rays (e.g., active SUMMARY galactic nuclei and pulsars)
|
From page 83... ...
From balloon and satellite observations over the last 25 years, researchers know that cosmic rays fill our galaxy with an energy density comparable to that in the turbulent motion of the interstellar gas and in magnetic fields. Gamma-ray measurements by the Compton Gamma Ray Observatory (CGRO)
|
From page 84... ...
The models are based on the idea that particles are confined by magnetic fields to remain in the vicinity of shock waves produced by converging or overtaking plasma flows. These theories were developed to explain in situ observations of energetic particles near planetary bow shocks and shocks in interplanetary space; it has been demonstrated that heavy ions can gain significant amounts of energy in such an environment.
|
From page 85... ...
For example, the energy density of galactic cosmic rays is sufficiently high that they must have an important dynamical role in the generation of the galactic magnetic field. They inflate this magnetic field and the plasma linked to it to form a galactic halo and possibly drive a galactic wind (Figure 21)
|
From page 86... ...
Cosmic rays enter the solar system carrying information about their origin and propagation through the galactic magnetic fields and interstellar matter. They are an accessible sample of matter from outside the immediate solar neighborhood.
|
From page 87... ...
Positrons can also contribute to cosmic rays as primary particles. Decay of radioactive supernova ejecta releases a large number of positrons at energies well above the injection threshold of most cosmic ray acceleration models.
|
From page 88... ...
The principal current questions in cosmic ray research are the following: How are solar energetic particles and galactic cosmic rays accelerated? Do supernova or stellar-wind shocks provide the bulk of the cosmic ray energy?
|
From page 89... ...
So far, inconclusive but promising attempts are being made to derive the elemental composition in that energy range from air shower data. A program is currently under way to measure the nuclear parameters that describe the propagation of cosmic ray nuclei through the matter in the interstellar medium.
|
From page 90... ...
By an aggressive but completely practical program of research, a full order of magnitude of overlap between those two techniques can be obtained in the coming decade. Observations using a large calorimeter on a space-based platform would test theories concerning the acceleration of galactic cosmic rays in supernovae shocks and provide details on the transformations of the source spectrum and composition that take place between the acceleration and the observation of the particles.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.