Abstract
A non-resonant instability for the amplification of the interstellar magnetic field in young supernova remnant (SNR) shocks was predicted by Bell, and is thought to be relevant for the acceleration of cosmic-ray (CR) particles. For this instability, the CRs streaming ahead of SNR shock fronts drive electromagnetic waves with wavelengths much shorter than the typical CR Larmor radius, by inducing a current parallel to the background magnetic field. We explore the nonlinear regime of the non-resonant mode using Particle-in-Cell hybrid simulations, with kinetic ions and fluid electrons, and analyze the saturation mechanism for realistic CR and background plasma parameters. In the linear regime, the observed growth rates and wavelengths match the theoretical predictions; the nonlinear stage of the instability shows a strong reaction of both the background plasma and the CR particles, with the saturation level of the magnetic field varying with the CR parameters. The simulations with CR-to-background density ratios of n(CR)/n(b) = 10(-5) reveal the highest magnetic field saturation levels, with energy also being transferred to the background plasma and to the perpendicular velocity components of the CR particles. The results show that amplification factors >10 for the magnetic field can be achieved, and suggest that this instability is important for the generation of magnetic field turbulence, and for the acceleration of CR particles.
| Language | English |
|---|---|
| Pages | L127-L132 |
| Number of pages | 6 |
| Journal | Astrophysics Journal Letters |
| Volume | 711 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 10 Mar 2010 |
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Keywords
- NONLINEAR SATURATION
- RESONANT KINETICALLY DRIVEN STREAMING INSTABILITY
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THE NONLINEAR SATURATION OF THE NON- RESONANT KINETICALLY DRIVEN STREAMING INSTABILITY. / Gargate, L.; Fonseca, R. A.; Niemiec, J.; Pohl, M.; Bingham, R.; Silva, L. O.
In: Astrophysics Journal Letters, Vol. 711, No. 2, 10.03.2010, p. L127-L132.Research output: Contribution to journal › Article
TY - JOUR
T1 - THE NONLINEAR SATURATION OF THE NON- RESONANT KINETICALLY DRIVEN STREAMING INSTABILITY
AU - Gargate, L.
AU - Fonseca, R. A.
AU - Niemiec, J.
AU - Pohl, M.
AU - Bingham, R.
AU - Silva, L. O.
PY - 2010/3/10
Y1 - 2010/3/10
N2 - A non-resonant instability for the amplification of the interstellar magnetic field in young supernova remnant (SNR) shocks was predicted by Bell, and is thought to be relevant for the acceleration of cosmic-ray (CR) particles. For this instability, the CRs streaming ahead of SNR shock fronts drive electromagnetic waves with wavelengths much shorter than the typical CR Larmor radius, by inducing a current parallel to the background magnetic field. We explore the nonlinear regime of the non-resonant mode using Particle-in-Cell hybrid simulations, with kinetic ions and fluid electrons, and analyze the saturation mechanism for realistic CR and background plasma parameters. In the linear regime, the observed growth rates and wavelengths match the theoretical predictions; the nonlinear stage of the instability shows a strong reaction of both the background plasma and the CR particles, with the saturation level of the magnetic field varying with the CR parameters. The simulations with CR-to-background density ratios of n(CR)/n(b) = 10(-5) reveal the highest magnetic field saturation levels, with energy also being transferred to the background plasma and to the perpendicular velocity components of the CR particles. The results show that amplification factors >10 for the magnetic field can be achieved, and suggest that this instability is important for the generation of magnetic field turbulence, and for the acceleration of CR particles.
AB - A non-resonant instability for the amplification of the interstellar magnetic field in young supernova remnant (SNR) shocks was predicted by Bell, and is thought to be relevant for the acceleration of cosmic-ray (CR) particles. For this instability, the CRs streaming ahead of SNR shock fronts drive electromagnetic waves with wavelengths much shorter than the typical CR Larmor radius, by inducing a current parallel to the background magnetic field. We explore the nonlinear regime of the non-resonant mode using Particle-in-Cell hybrid simulations, with kinetic ions and fluid electrons, and analyze the saturation mechanism for realistic CR and background plasma parameters. In the linear regime, the observed growth rates and wavelengths match the theoretical predictions; the nonlinear stage of the instability shows a strong reaction of both the background plasma and the CR particles, with the saturation level of the magnetic field varying with the CR parameters. The simulations with CR-to-background density ratios of n(CR)/n(b) = 10(-5) reveal the highest magnetic field saturation levels, with energy also being transferred to the background plasma and to the perpendicular velocity components of the CR particles. The results show that amplification factors >10 for the magnetic field can be achieved, and suggest that this instability is important for the generation of magnetic field turbulence, and for the acceleration of CR particles.
KW - NONLINEAR SATURATION
KW - RESONANT KINETICALLY DRIVEN STREAMING INSTABILITY
U2 - 10.1088/2041-8205/711/2/L127
DO - 10.1088/2041-8205/711/2/L127
M3 - Article
VL - 711
SP - L127-L132
JO - Astrophysics Journal Letters
T2 - Astrophysics Journal Letters
JF - Astrophysics Journal Letters
SN - 2041-8205
IS - 2
ER -