Issue |
A&A
Volume 474, Number 2, November I 2007
|
|
---|---|---|
Page(s) | 339 - 343 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20077776 | |
Published online | 28 August 2007 |
Constraints on cosmic-ray positron excess and average pulsar parameters
Istituto di Fisica dell'Università di Urbino, via S. Chiara, Urbino 61029, Italy e-mail: cgrimani@fis.uniurb.it
Received:
2
May
2007
Accepted:
6
August
2007
Recent, accurate ratio measurements in cosmic
rays allow us to distinguish among different estimates of secondary positron
production in the interstellar medium (ISM), provided the effect of solar
modulation and solar polarity are properly
taken into account. Data above a few GeV
indicate that a possible extra component of positrons could be required
in addition to the secondaries. This positron excess is compatible
with the hypothesis of pair production at the polar cap of mature
pulsars. Assuming only pulsar
contributions without any exotic contributions such as dark-matter annihilation, the average parameters of Galactic pulsars contributing to positron and electron
interstellar fluxes were obtained.
These parameter values are found
near the peak of the
distributions of the observed characteristics of radio pulsars. The studied gamma-ray
pulsar sample is too small to make any conclusion.
The expected
ratio from the PAMELA
experiment currently in orbit is reported in this paper. The GLAST mission will allow us
to double-check our findings about the role of pair production
at the pulsar polar cap and outer gap.
Key words: cosmic rays / Sun: activity / Sun: magnetic fields / Sun: solar-terrestrial relations / stars: pulsars: general
© ESO, 2007
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