Observations and Observability of Magnetic Waves due to Newborn Interstellar Pickup Ions

Abstract:

We bring together several newly published and recently submitted papers in an effort to
develop a refined view of the magnetic waves excited by newborn interstellar pickup ions. First,
we show examples of wave events from 3 separate catalogs we have developed: (1) waves excited by
pickup H+ and observed by the Ulysses spacecraft inside 5.5AU, (2) waves excited by both pickup
H+ and pickup He+ that are observed by the Voyager 1 & 2 spacecraft inside 7AU, and (3)
waves excited by pickup He+ and seen by the ACE spacecraft at 1AU. It is now well-established
that the dissipation of this wave energy is essential to the observed heating of the thermal plasma
in the outer helioshere. However, the traditional theory for these waves suggests that they should
be ubiquitous when they are, in fact, quite rare and difficult to find. We compare wave growth rates
to turbulent cascade rates and argue that under most conditions the turbulence is too aggressive to
allow the waves to achieve observable amplitudes.