Robert Main (MPIfR)

Robert Main Colloquium: Scintillation Arcs: Scattering Screens and Surprises

Marsfield

Abstract

Radio emission from pulsars scintillates in time and frequency – an
interference pattern arising from small-scale inhomogeneities in electron
density in the interstellar medium. The discovery of "scintillation arcs"
showed that scintillation is often remarkably ordered, well described by
scattering in highly anisotropic thin screens. Scintillation arcs are a
powerful probe of small-scale structures in the ionized interstellar medium,
and can be used to determine the location of screens, measure the variable
time delays from scattering, and measure pulsar orbits on the plane of the
sky. In this talk, I will show the first scintillation results from the
Thousand Pulsar Array at MeerKAT, with scintillation arcs seen in upwards of
100 pulsars. I will then describe a long-term multi-frequency study of the
high-velocity pulsar B1508+55 with LOFAR and Effelsberg, solving the observed
scintillation from two interacting screens, and where low frequency `echoes'
preceded a change in scintillation by ~3 years. Motivated by this study, I
will describe ongoing efforts to connect scintillation across many scales in
frequency, and the most promising future avenues.