Measuring lens dimensionality in extreme scattering events through wave optics

TL;DR

This paper explores how wave optics effects in extreme scattering events can help distinguish between one-dimensional and two-dimensional plasma lenses in the interstellar medium, providing new insights beyond traditional geometric optics.

Contribution

It demonstrates that wave effects can differentiate lens dimensionality with minimal assumptions, advancing the understanding of plasma lensing in astrophysics.

Findings

Wave effects can distinguish lens dimensionality.

Minimal assumptions needed for lens classification.

Potential to improve interpretation of ESE observations.

Abstract

Compact radio sources have been observed to undergo large, frequency dependent changes in intensity due to lensing by structures in the interstellar medium, in so-called "extreme scattering events" (ESEs). While the study of astrophysical plasma lensing has primarily focused on the geometric limit of optics, coherent radio sources such as pulsars exhibit wave effects when lensed. The additional phase information provided by interference effects in the wave regime may yield more information about the lens than could be obtained in the geometric regime. In this paper, we show that, using wave effects, one can potentially distinguish a one-dimensional lens (where "one-dimensional" includes both highly elongated lenses, as well as perfectly axisymmetric lenses) from a fully two-dimensional lens, with minimal assumptions on the form of the lensing potential.