2-3 kHz radiation from the outer heliosphere

• We developed a new theory for why the 2-3 kHz radio emissions turn on when a shock driven by a GMIR passes beyond the heliopause [Cairns and Zank, 2001a,b]. The theory provides a detailed theoretical basis for Gurnett et al.'s [Science, 1993] model for the radiation. The theory is based on ``lower-hybrid drive'' producing a fast electron tail in the outer heliosheath that is then accelerated by the GMIR shock, the lower hybrid waves being driven by pickup ions. Scattering and propagation effects are argued to permit primarily fundamental radiation to move into the inner heliosphere, not inconsistent with the available data.
• Simulations of shock propagation through the inhomogeneous solar wind were combined with spacecraft data to predict a new 2-3 kHz radiation event in September 2001 [Zank et al., 2001]. However, examination of the Voyager wave data shows that any radiation produced then remained below background.

---