Speaker
Description
We investigate the damping of Alfvén waves generated by the
cosmic ray resonant streaming instability as due to ion-neutral
damping, turbulent damping and non linear Landau damping, in the
warm ionised and warm neutral phases of the interstellar medium.
We do so in the context of the cosmic ray escape and propagation
in the proximity of supernova remnants. For the ion-neutral damping,
state-of-the-art damping coefficients are used, where the momentum
transfer and charge exchange cross sections between various species
of ions and neutrals are computed in detail or measured. We
investigate whether the self-confinement of cosmic rays nearby
sources can appreciably affect the grammage. In fact, if this is
the case, the standard picture, in which CR secondaries are produced
during the whole time spent by cosmic rays throughout the Galactic
disk, should be deeply revisited. We show that the ion-neutral
damping and the turbulent damping effectively limit the residence
time of cosmic rays in the source proximity, so that the grammage
accumulated near sources is found to be negligible. This also
happens in the most optimistic scenario where ion-neutral damping
is less effective, namely in a medium with only neutral helium
and fully ionized hydrogen, contrary to what was previously suggested.
Keywords
cosmic rays; ISM: general
| Subcategory | Theoretical Results |
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