Backward wave cyclotron-maser emission in the auroral magnetosphere.
In this Letter, we present theory and particle-in-cell simulations describing cyclotron radio emission from Earth's auroral region and similar phenomena in other astrophysical environments. In particular, we find that the radiation, generated by a down-going electron horseshoe distribution is due to a backward-wave cyclotron-maser emission process. The backward wave nature of the radiation contributes to upward refraction of the radiation that is also enhanced by a density inhomogeneity. We also show that the radiation is preferentially amplified along the auroral oval rather than transversely. The results are in agreement with recent Cluster observations.
Department of Physics, SUPA, University of Strathclyde, Glasgow, Scotland G4 0NG, United Kingdom.
D C
DC
Speirs
Department of Physics, SUPA, University of Strathclyde, Glasgow, Scotland G4 0NG, United Kingdom and Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, England OX11 0QX, United Kingdom.
R
R
Bingham
School of Mathematics and Statistics, University of St. Andrews, Fife, Scotland KY16 9SS, United Kingdom.
R A
RA
Cairns
School of Mathematics and Statistics, University of St. Andrews, Fife, Scotland KY16 9SS, United Kingdom.
I
I
Vorgul
Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, England OX11 0QX, United Kingdom.
B J
BJ
Kellett
Department of Physics, SUPA, University of Strathclyde, Glasgow, Scotland G4 0NG, United Kingdom.
A D R
AD
Phelps
Department of Physics, SUPA, University of Strathclyde, Glasgow, Scotland G4 0NG, United Kingdom.
K
K
Ronald