EDP Sciences
Free access
Volume 417, Number 3, April III 2004
Page(s) 807 - 817
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361:20040018

A&A 417, 807-817 (2004)
DOI: 10.1051/0004-6361:20040018

Cosmic ray acceleration by spiral shocks in the galactic wind

H. J. Völk1 and V. N. Zirakashvili2

1  Max-Planck-Institut für Kernphysik, 69029, Heidelberg, Postfach 103980, Germany
    e-mail: Heinrich.Voelk@mpi-hd.mpg.de
2  Institute for Terrestrial Magnetism, Ionosphere and Radiowave Propagation, 142190, Troitsk, Moscow Region, Russia

(Received 17 March 2003 / Accepted 15 January 2004)

Cosmic ray acceleration by shocks related with Slipping Interaction Regions (SIRs) in the Galactic Wind is considered. SIRs are similar to Solar Wind Corotating Interaction Regions. The spiral structure of our Galaxy results in a strong nonuniformity of the Galactic Wind flow and in SIR formation at distances of 50 to 100 kpc. SIRs are not corotating with the gas and magnetic field because the angular velocity of the spiral pattern differs from that of the Galactic rotation. It is shown that the collective reacceleration of the cosmic ray particles with charge $Z\rm e$ in the resulting shock ensemble can explain the observable cosmic ray spectrum beyond the "knee" up to energies of the order of $10^{17}\,Z$ eV. For the reaccelerated particles the Galactic Wind termination shock acts as a reflecting boundary.

Key words: ISM: cosmic rays -- acceleration of particules

Offprint request: V. N. Zirakashvili, Zirak@izmiran.rssi.ru

© ESO 2004