Non-linear diffusion of cosmic rays escaping from supernova remnants - II. Hot ionized media
Date Issued
2019
Author(s)
Abstract
We study the problem of the escape and transport of Cosmic-Rays (CR) from a
source embedded in a fully ionised, hot phase of the interstellar medium (HIM).
In particular, we model the CR escape and their propagation in the source
vicinity taking into account excitation of Alfv\'enic turbulence by CR
streaming and mechanisms damping the self-excited turbulence itself. Our
estimates of escape radii and times result in large values (100 pc,
$2\times10^5$ yr) for particle energies $\lesssim20$ GeV and smaller values for
particles with increasing energies (35 pc and 14 kyr at 1 TeV). These escape
times and radii, when used as initial conditions for the CR propagation outside
the source, result in relevant suppression of the diffusion coefficient (by a
factor 5-10) on time-scales comparable with their (energy dependent) escape
time-scale. The damping mechanisms are fast enough that even on shorter time
scales the Alfv\'enic turbulence is efficiently damped, and the ratio between
random and ordered component of the magnetic field is $\delta B/B_0\ll 1$,
justifying the use of quasi-linear theory. In spite of the suppressed diffusion
coefficient, and then the increased residence time in the vicinity (<200 pc) of
their source, the grammage accumulated by CRs after their escape is found to be
negligible (at all energies) as compared to the one accumulated while diffusing
in the whole Galaxy, due to the low density of the HIM.
Funding(s)
Volume
484
Issue
2
Start page
2684
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.484.2684N
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
1903.03193.pdf
Size
349.32 KB
Format
Adobe PDF
Checksum (MD5)
a79decedb6f0a6f10f9883e7466bc0ce
Loading...
Name
stz137.pdf
Description
Pdf editoriale
Size
1.39 MB
Format
Adobe PDF
Checksum (MD5)
0ae28cb5a38af424dd8e68b4571af400