The effects of plasma lensing on the inferred dispersion measures of Fast Radio Bursts

Understand

Radio signals are delayed when propagating through plasma.

• This type of delay is frequency-dependent and is usually used for estimating the projected number density of electrons along the line of sight, called the dispersion measure.
• The dense and clumpy distribution of plasma can cause refractive deflections of radio signals, analogous to lensing effects.
• Similar to gravitational lensing, there are two contributions to the time delay effect in plasma lensing: a geometric delay, due to increased path length of the signal, and a dispersive delay due to the change of speed of light in a plasma medium.