|
For a radio source that emits polarized radiation, a parameter indicating the extent to which the polarization vector has rotated while the radiation has been travelling from the source to the observer. The degree of rotation is proportional to the magnetic field across the line of sight and to the electron density along the line of sight. It depends on the square of wavelength, so observations of polarization at several wavelengths enable the rotation measure towards a radio source to be determined. Rotation measures are the main source of information on the strength and direction of the magnetic field in our Galaxy.
|