ar X iv : a st ro - p h / 97 10 12 4 v 1 1 3 O ct 1 99 7 Production and propagation of cosmic - ray positrons and electrons
نویسندگان
چکیده
We have made a new calculation of the cosmic-ray secondary positron spectrum using a diffusive halo model for Galactic cosmic-ray propagation. The code computes self-consistently the spectra of primary and secondary nucleons, primary electrons, and secondary positrons and electrons. The models are first adjusted to agree with the observed cosmic-ray Boron/Carbon ratio, and the interstellar proton and Helium spectra are then computed; these spectra are used to obtain the source function for the secondary positrons/electrons which are finally propagated with the same model parameters. The primary electron spectrum is evaluated, again using the same model. Fragmentation and energy losses are computed using realistic distributions for the interstellar gas and radiation fields, and diffusive reacceleration is also incorporated. Our study includes a critical re-evaluation of the secondary decay calculation for positrons. The predicted positron fraction is in good agreement with the measurements up to 10 GeV, beyond which the observed flux is higher than that calculated. Since the positron fraction is now accurately measured in the 1–10 GeV range our primary electron spectrum should be a good estimate of the true interstellar spectrum in this range, of interest for gamma ray and solar modulation studies. We further show that a harder interstellar nucleon spectrum, similar to that suggested to explain EGRET diffuse Galactic gamma ray observations above 1 GeV, can reproduce the positron observations above 10 GeV without requiring a primary positron component.
منابع مشابه
ar X iv : a st ro - p h / 97 09 21 1 v 1 22 S ep 1 99 7 Modelling cosmic rays and gamma rays in the Galaxy Andrew
An extensive program for the calculation of galactic cosmic-ray propagation has been developed. This is a continuation of the work described in [1]. The main motivation for developing this code [2] is the prediction of diffuse Galactic gamma rays for comparison with data from the cgro instruments egret, comptel, and osse. The basic spatial propagation mechanisms are (momentumdependent) diffusio...
متن کاملar X iv : a st ro - p h / 01 01 06 8 v 1 4 J an 2 00 1 MODELS FOR GALACTIC COSMIC - RAY PROPAGATION
A new numerical model of particle propagation in the Galaxy has been developed, which allows the study of cosmic-ray and gamma-ray production and propagation in 2D or 3D, including a full reaction network. This is a further development of the code which has been used for studies of cosmic ray reacceleration, Galactic halo size, antiprotons and positrons in cosmic rays, the interpretation of dif...
متن کاملar X iv : a st ro - p h / 97 10 27 7 v 1 2 4 O ct 1 99 7 High - Energy Interactions and Extensive Air Showers 1
In this report a summary of recent developments in the fields of high-energy nuclear interactions (HE 1) and air shower phenomenology (HE 2) is presented. New results from accelerator and cosmic-ray experiments and the progress in the theoretical understanding and simulation are reviewed and their impact on air shower analysis is discussed.
متن کاملar X iv : a st ro - p h / 03 02 30 7 v 1 1 6 Fe b 20 03 The Local Interstellar Spectrum of Cosmic Ray Electrons . Direct measurements
The local interstellar spectrum of cosmic ray electrons is derived by correcting the data from balloon and space measurements for the solar modulation effect. The resulting spectrum, after the renormalization of some experimental data set, can be fitted with a single power law from about 3 GeV to 2 TeV with spectral index γ = 3.42± 0.02. On the other hand, at low energies the measurements by CA...
متن کامل