Issue |
A&A
Volume 394, Number 3, November II 2002
|
|
---|---|---|
Page(s) | 1039 - 1056 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20021176 | |
Published online | 21 October 2002 |
New results on source and diffusion
spectral features of Galactic cosmic rays: I
ratio
1
Laboratoire de Physique Théorique , 74941 Annecy-le-Vieux, France
2
Université de Savoie, 73011 Chambéry, France
3
Università degli Studi di Torino and INFN, Torino, Italy
Corresponding author: R. Taillet, taillet@lapp.in2p3.fr
Received:
18
June
2002
Accepted:
29
July
2002
In a previous study (Maurin et al. 2001), we explored
the set of parameters describing diffusive propagation of cosmic rays
(galactic convection, reacceleration, halo thickness, spectral index and
normalization of the diffusion coefficient), and we identified those
giving a good fit to the measured ratio.
This study is now extended to take into
account a sixth free parameter, namely the spectral index of sources.
We use an updated version of our code where the reacceleration
term comes from standard minimal reacceleration models.
The goal of this paper is to present a general view of the evolution
of the goodness of fit to
data with the propagation parameters.
In particular, we find that, unlike the well accepted
picture, and in accordance with
our previous study, a Kolmogorov-like power spectrum for diffusion
is strongly disfavored. Rather, the
analysis points towards
along with source spectra
index
2.0.
Two distinct energy dependences are used for the source spectra:
the usual power-law in rigidity and a law modified
at low energy, the second choice being only slightly preferred.
We also show that the results are not much affected by a different
choice for the diffusion scheme.
Finally, we compare our findings to recent works, using other propagation models.
This study will be further refined in a
companion paper, focusing on the fluxes of cosmic ray nuclei.
Key words: ISM: cosmic rays
© ESO, 2002
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