Rotation Measure

An FRB propogating through a magnetised cold-plasma will undergo a phenomena known as Faraday rotation, where the Linear polarisation position angle is rotated due to the magnetic field parallel/anti-parallel to the FRB line of sight. This is usually quantified using the Rotation Measure. The rotation measures for a cold plasma is well described by the following equation

\[\chi(\nu) = \mathrm{RMc^{2}}\Bigg(\frac{1}{\nu^{2}} - \frac{1}{\nu_{0}^{2}}\Bigg)\]

where \(RM\) is the rotation measure, \(\chi\) is the Linear polarisation position angle and \(\nu_{0}\) the reference frequency.