Colloquium: High-resolution study with interstellar lenses

© CC-BY-SA-NC credit: Dongzi Li

Radio waves propagating in space are often scattered into multiple paths by the ionized interstellar medium. It has long been realized that the scattering screens could be used as “interstellar lenses” to study the source and the interstellar plasma.

Compared to the telescopes on Earth, interstellar lenses could be of much larger sizes, ranging from solar radius to AUs, which could result in high angular resolution and sensitivity. Moreover, the interstellar lenses sometimes have the advantage of placement. For example, for sources with a close companion, the interstellar lenses formed in the companion wind could be only a few solar radii away from the source -- the proximity provides better resolution than studying the Sun with telescopes on Earth.

Despite the great advantages of the interstellar lenses, the uncertainty on the lensing structures restricts applications to extremely simple sources, such as the point-like, coherent sources: pulsars, and potentially FRBs.

In this talk, I will discuss applications of interstellar lensing. In particular, I will discuss the ability to constraining the pulsar emission region and measuring the Doppler factor of the emitting particles. I will also talk about the lenses' sensitivity to constrain the magneto-environment of the lensing material.