Cosmic rays in star-forming galaxies

Massimo Persic*, Yoel Rephaeli

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


The energy density of cosmic ray protons (CRp) in star-forming environments can be (i) measured from γ-ray πo-decay emission, (ii) inferred from the measured radio non-thermal synchrotron emission (once a theoretical p/e ratio and particle-field equipartition have been assumed), and (iii) estimated from the observed supernova rate and the deduced CRp residency time. For most of the currently available galaxies where these methods can be simultaneously applied, the results of the various methods agree and suggest that CRp energy densities range from script O sign (10-1) eV cm -3 in very quiet environments up to script O sign (102) eV cm-3 in very active ones. The only case for which the methods do not agree is the Small Magellanic Cloud, where the discrepancy between measured and estimated CRp energy density may be due to a smaller characteristic CR confinement volume.

Original languageEnglish
Article number012038
JournalJournal of Physics: Conference Series
Issue number1
StatePublished - 2012
EventInternational Workshop on Beamed and Unbeamed Gamma-Rays from Galaxies - Muonio, Finland
Duration: 11 Apr 201115 Apr 2011


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