Propagation of cosmic rays in the galaxy

Daniel, R. R.; Stephens, S. A.

doi:10.1007/bf00718837

Cited by 35 publications

(14 citation statements)

References 291 publications

(312 reference statements)

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“…As a result, the production spectrum of Ps does not show depletion at low energies due to kinematic restrictions. Dermer and Ramaty (1986a) have examined this idea and calculated the production rates of ffs for different plasma temperatures. These results are shown in Figure 12.…”

Section: Kinetic Energy In Gevmentioning

confidence: 99%

“…We consider in this section working model of this kind, by which equilibrium spectrum can be derived by simple methods, to predict the fi spectrum in the Galaxy. In order to explain the observed variation of the ratio of secondary to primary nuclei with energy, two types of energy dependence were suggested (see Daniel and Stephens, 1975). The first one relates to energy dependent confinement in the Galaxy (e.g., Audouze and Cesarsky, 1973) and is called 'modified leaky box model' (MLBM).…”

Section: Standard Modelsmentioning

confidence: 99%

“…This would lead to incorrect solution as the cumulative errors cannot be reduced to zero by letting dt ~ 0, since the number of steps tends to oc. If one assume that the third term can be evaluated separately and included as a part of the production term, it is possible to use the solution given by Daniel and Stephens (1975) through iteration procedure (Tan and Ng, 1983a). In the following calculations, we use r/= 2.50 to take into account the cosmic-ray composition, decay of antineutrons and the composition of interstellar gas.…”

Section: ) and F(ee')dementioning

confidence: 99%

“…In Equation (4.1) one needs to include the energy loss due to synchrotron radiation and inverse Compton scattering in the second term. The attenuation term (fourth term) is replaced by Ne+ (E)ab(E)dE, where ab(E ) is the bremsstrahlung radiation cross-section and the third term in replaced by (Daniel and Stephens, 1974) i Ne+ e' -E) de', E where ~b b is the differential probability that a positron of energy E' radiates a photon of energy (E' -E). Each confinement volume is described by the values of the gas density, magnetic field strength and photon density.…”

Section: Positron Componentmentioning

confidence: 99%

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The role of antiprotons in cosmic-ray physics

Stephens

Golden

1988

Space Sci Rev

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Though success eluded experimentalists from detecting cosmic-ray antiprotons over a long period of time, the study of cosmic-ray antiprotons has now become a fascinating field of research. In this review, we have attempted to elucidate the excitement in this area of research since the discovery of antiprotons in the laboratory. We have described the experiments carried out so far to measure the energy spectrum of antiprotons, from about 200 MeV to about 15 GeV, and summarised the results. The observed spectrum, with the limited data, appears to be very hard and is different from other components of cosmic radiation. Upper limits to the fraction of antiprotons in cosmic-rays have also been derived at higher energies, using the observed spectra of cosmic-ray primary and secondary particles at different depths in the atmosphere. We have described various physical processes by which antiprotons could be produced, such as high-energy interactions, neutron oscillations, evaporation of Mini Black Holes, decay of super symmetric particles, etc. The energy spectrum of antiprotons, which are produced through the above processes, undergoes modifications during propagation in the Galaxy. We have examined in detail the propagation models which have been employed to explain the observed data. It is shown that no single model could predict correctly the observed energy spectrum of antiprotons over the entire energy region. However, many models are able to explain the data at relativistic energies. It is difficult at this stage to make a choice among these models. The implications of these models for other components of cosmic-rays, such as positrons, deuterium, and He, have been discussed. We have examined the production of gamma rays in the Galaxy from sources, which produce the observed antiprotons through high-energy interactions. We have also briefly indicated the effect of possible re-acceleration during their confinement in the Galaxy. We finally emphasized the need for more detailed measurements of the spectral shape of cosmic-ray antiprotons to further refine speculations of their origin. Similarly, we have shown that detailed observation of the energy spectra of positrons, deuterium, and He at relativistic energies are crucial to test various propagation models.

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Section: Kinetic Energy In Gevmentioning

confidence: 99%

Section: Standard Modelsmentioning

confidence: 99%

Section: ) and F(ee')dementioning

confidence: 99%

Section: Positron Componentmentioning

confidence: 99%

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The role of antiprotons in cosmic-ray physics

Stephens

Golden

1988

Space Sci Rev

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“…The total electron production function for AE and KO electrons is shown in Figure 4, where we used the results of Daniel & Stephens (1975). The distribution function of these relativistic positrons is described by equation (9) ; w ph þ 6:2 ; 10 11…”

Section: Production Function Of Secondary Electronsmentioning

confidence: 99%

Annihilation Emission from the Galactic Black Hole

Cheng

Chernyshov

Dogiel

2006

ApJ

112

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Both diffuse high-energy gamma rays and an extended electron-positron annihilation line emission have been observed in the Galactic Center (GC) region. Although X-ray observations indicate that the Galactic black hole Sgr A Ã is inactive now, we suggest that Sgr A Ã can become active when a captured star is tidally disrupted and matter is accreted into the black hole. As a consequence the Galactic black hole could be a powerful source of relativistic protons. We are able to explain the current observed diffuse gamma rays and the very detailed 511 keV annihilation line of secondary positrons by p-p collisions of such protons, with appropriate injection times and energy. Relativistic protons could have been injected into the ambient material if the black hole captured a 50 M star at several tens times 10 6 yr ago. An alternative possibility is that the black hole continues to capture stars with $1 M every 10 5 yr. Secondary positrons produced by p-p collisions at energies k30 MeV are cooled down to thermal energies by Coulomb collisions and are annihilated in the warm neutral and ionized phases of the interstellar medium with temperatures about several eV, because the annihilation cross section reaches its maximum at these temperatures. It takes about 10 million years for the positrons to cool down to thermal temperatures so that they can diffuse into a very large extended region around the GC. A much more recent star capture may also be able to account for recent TeVobservations within 10 pc of the GC, as well as for the unidentified GeV gamma-ray sources found by EGRET at GC. The spectral difference between the GeV and TeV flux could be explained naturally in this model as well.

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7.7 Interstellar magnetic field

Schmid-Burgk¹

Interstellar Matter, Galaxy, Universe

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Propagation of cosmic rays in the galaxy

Cited by 35 publications

References 291 publications

The role of antiprotons in cosmic-ray physics

The role of antiprotons in cosmic-ray physics

Annihilation Emission from the Galactic Black Hole

7.7 Interstellar magnetic field

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