Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2009-11-23
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
accepted for publication in A&A (final version)
Scientific paper
Supernova remnants are believed to be a major source of cosmic-rays in the Galaxy. As their progenitors are commonly found clustered in OB associations, one has to consider the possibility of collective effects in the acceleration process. In this work we investigate the shape of the spectrum of protons accelerated inside the superbubbles blown around clusters of massive stars. To do so we embed semi-analytical models of particle acceleration and transport inside Monte-Carlo simulations of OB associations timelines. We consider regular acceleration at the shock front of supernova remnants, as well as stochastic re-acceleration and escape occurring between the shocks. We observe that particle spectra, although strongly intermittent, get a distinctive shape resulting from a competition between acceleration and escape: they are harder at the lowest energies and softer at the highest energies. The momentum at which this spectral break occurs depends on a single dimensionless parameter, which we evaluate for a selection of objects. The behaviour of a superbubble regarding acceleration depends on the magnetic turbulence: if B is low the superbubble is simply the host of a collection of individual supernovae shocks, but if B is high enough it acts as a global accelerator, producing distinctive spectra ? which has important implications on the high-energy emission from these objects.
Ferrand Gilles
Marcowith Alexandre
No associations
LandOfFree
On the shape of the spectrum of cosmic-rays accelerated inside superbubbles does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On the shape of the spectrum of cosmic-rays accelerated inside superbubbles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the shape of the spectrum of cosmic-rays accelerated inside superbubbles will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-173527