On the inefficiency of particle re-acceleration mechanisms in the cores of massive stellar clusters
Abstract
We consider scenarios for non-thermal particle acceleration and re-acceleration in the central cores of compact massive star clusters, aided by insights from high-resolution hydrodynamic simulations. We show that (i) particles are unlikely to interact with many shocks during their lifetimes in the core; (ii) colliding flows do not produce hard spectra; and (iii) turbulent re-acceleration in the core is suppressed. Inefficient re-acceleration mechanisms are not expected to produce hard components nor to increase the maximum energy within the cores of massive star clusters. Models in which the observed ultra-high-energy gamma rays originate in the core of massive stellar clusters are thus disfavoured.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2024
- DOI:
- 10.1093/mnras/stae1039
- arXiv:
- arXiv:2404.09885
- Bibcode:
- 2024MNRAS.530.4747V
- Keywords:
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- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 16 pages, 14 figures, accepted in MNRAS