Issue |
A&A
Volume 423, Number 2, August IV 2004
|
|
---|---|---|
Page(s) | 405 - 413 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20047005 | |
Published online | 06 August 2004 |
Cosmic rays from Galactic pulsars
Department of Experimental Physics, University of Łódź, ul. Pomorska 149/153, 90-236 Łódź, Poland e-mail: bednar@fizwe4.fic.uni.lodz.pl
Received:
5
January
2004
Accepted:
11
May
2004
We calculate energy spectra and mass composition of cosmic rays accelerated by the
galactic population of pulsars during their radio and gamma-ray phase.
It is assumed that a significant part of the pulsar rotational energy
is lost on acceleration of iron nuclei extracted from the surface of the neutron star.
The nuclei are accelerated, at first when passing the outer gap of the inner pulsar
magnetosphere and later in the pulsar wind zone, to energies corresponding to 50% of the total potential drop through the polar cap region of the neutron star.
We calculate energy spectra of the nuclei injected from the pulsar wind nebulae into
the Galaxy including different
energy loss processes of nuclei during their propagation in the pulsar magnetosphere
and the expanding nebula, their fragmentation in collisions with radiation
and matter, adiabatic energy losses, and escape from the nebula.
Several models proposed for the distribution of the initial parameters
of the galactic pulsar population are considered. It is shown that the best description
of the observed cosmic ray spectrum and the mass composition between a few 1015 eV
and a few 1018 eV is obtained for the model B of Lorimer et al., in which the logs of initial pulsar periods and surface magnetic
fields are given by the Gaussian distributions with the average values of
= 2.6 and
= 12.3, respectively. In order to supply the cosmic rays
into the Galaxy with the required rate, the product of the efficiency of cosmic ray
acceleration by pulsars and their birth rate should be about 10-2 yr-1.
Key words: stars: supernovae: general / acceleration of paricles / stars: pulsars: general / ISM: cosmic rays
© ESO, 2004
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