EDP Sciences
Free access
Volume 424, Number 3, September IV 2004
Page(s) 747 - 760
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361:20041269

A&A 424, 747-760 (2004)
DOI: 10.1051/0004-6361:20041269

Superbubbles and energetic particles in the Galaxy

I. Collective effects of particle acceleration
E. Parizot1, A. Marcowith2, E. van der Swaluw3, 4, A. M. Bykov5 and V. Tatischeff6

1  Institut de Physique Nucléaire d'Orsay, IN2P3-CNRS/Université Paris-Sud, 91406 Orsay Cedex, France
    e-mail: parizot@ipno.in2p3.fr
2  Centre d'Étude Spatiale des Rayonnements, 9 av. du Colonel Roche, 31028 Toulouse Cedex 4, France
3  Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
4  FOM-Institute for Plasma Physics Rijnhuizen, PO Box 1207, 3430 BE Nieuwegein, The Netherlands
5  AF Ioffe Institute for Physics and Technology, St. Petersburg, 194021, Russia
6  Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, IN2P3-CNRS, 91405 Orsay, France

(Received 11 May 2004 / Accepted 26 May 2004)

Observations indicate that most massive stars in the Galaxy appear in groups, called OB associations, where their strong wind activity generates large structures known as superbubbles, inside which the subsequent supernovae (SNe) explode, with a tight space and time correlation. We investigate four main questions: 1) does the clustering of massive stars and SN explosions influence the particle acceleration process usually associated with SNe, and induce collective effects which would not manifest around isolated supernova remnants?; 2) does it make a difference for the general phenomenology of Galactic Cosmic Rays (GCRs), notably for their energy spectrum and composition?; 3) Can this help alleviate some of the problems encountered within the standard GCR source model?; and 4) Is the link between superbubbles and energetic particles supported by observational data, and can it be further tested and constrained? We argue for a positive answer to all these questions. Theoretical, phenomenological and observational aspects are treated in separate papers. Here, we discuss the interaction of massive stellar winds and SN shocks inside superbubbles and indicate how this leads to specific acceleration effects. We also show that due to the high SN explosion rate and low diffusion coefficient, low-energy particles experience repeated shock acceleration inside superbubbles.

Key words: ISM: cosmic rays -- acceleration of particles -- ISM: supernovae remnants -- shock waves -- ISM: bubbles

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