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Astron. Astrophys. 346, 211-218 (1999)

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Time-dependent models for the interaction of energetic particles in the ISM

Etienne Parizot 1 and Roland Lehoucq 2

1 Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland (parizot@cp.dias.ie)
2 Service d'Astrophysique, CEA/DSM/DAPNIA, F-91191 Gif-sur-Yvette, France (roller@discovery.saclay.cea.fr)

Received 30 November 1998 / Accepted 19 March 1999


We present a general model allowing one to calculate the distribution function of energetic particles (EPs) in the interstellar medium (ISM), and hence any relevant nuclear reaction rate, for any given time-dependent injection function, as well as in situations when the propagation coefficients themselves are non stationary. We review and provide physical interpretation of general formal solutions of a propagation equation taking into account energy losses, nuclear destruction and escape. Both one-zone and extended models are investigated. Our main goal is to provide standard and general tools for subsequent use in nuclear astrophysics, notably to calculate the gamma-ray emission and spallation rates associated with energetic events and specific acceleration mechanisms. Considering the stationary limit of the model, we show that only time-dependent calculations can probe the density dependence of the physical processes under study, while steady-state models can in principle only give information about density-independent processes.

Key words: nuclear reactions, nucleosynthesis, abundances – ISM: cosmic rays

© European Southern Observatory (ESO) 1999

Online publication: May 6, 1999