Up-going whistler-mode waves and their interactions with upward-moving energetic electrons: a study on the polar environment of Jupiter's magnetosphere

Over the entire Jovian polar region, the Juno spacecraft observed intense broadband upward-propagating whistler-mode waves associated with upward-traveling energetic electrons. The waves are propagating in the whistler mode, with auroral hiss-like characteristics. Hiss is known to be generated by electron energy beams (inverted-Vs) via an instability at the Landau resonance. We discuss a mechanism for how the waves are produced and how the waves can interact with the electrons by changing their energy and pitch angle. The mechanism begins with a downward field-aligned current over the polar cap, generating strong downward parallel electric fields and upward-traveling electron beams. The inverted-Vs then produce broadband upward-traveling whistler-mode auroral hiss by a beam-plasma instability at the Landau resonance. As the waves propagate upwards, their phase velocity increases, which has the potential to carry trapped electrons to high energies. The waves have also been shown to participate in pitch angle scattering of the electrons, causing them to deviate from the first adiabatic invariant motion. We will also present numerical calculations of wave growth rates and show that they are sufficient to produce the observed wave intensities. Currently, there are sufficient data to conduct a statistical study on the wave-particle interactions occurring throughout Jupiter's polar regions. We will discuss the similarities and differences between perijoves in order to better understand the whistler-mode hiss emissions and their interactions with electrons.