Bill Coles (UCSD/ATNF)

The Interstellar Medium, Turbulence, and Radio Scattering - Bill Coles colloquium

ATNF Marsfield Lecture Theatre

Abstract

The interstellar medium appears to be turbulent on a range of scales which is
large, even by astronomical standards. Different observers have quite different views of
the medium. Spectroscopists are able to get a measure of line-of-sight velocity variations
at large scales - typically 10's of parsec. Observations of intensity scintillation (ISS) of
compact sources such as pulsars or AGN's provide a measure of electron density
fluctuations at much smaller scales - typically 105 km. Pulsar observers are also able
to measure variations in the electron column density or "dispersion measure" over
intermediate scales - typically 10 AU. Tiny scales for the spectroscopist are giant
scales for the pulsar person. I will speculate wildly on some of these issues biassed by
my view from the bottom of the ISM range and my experience with the solar wind.