g / s b⋅ = τ ) ( cos 2 t E V ω = ] ) ( cos[ 1 g t E V τ ω − = ] ) 2 ( cos ) ( [cos g g t P ωτ ω ωτ − + multiply average The path lengths from sensors to multiplier are assumed equal! Geometric Time Delay Rapidly varying, with zero mean Unchanging ) ( cos g C P R ωτ =
wave interaction with free electrons makes for slower group velocities for lower frequencies. Time delay is calculated by: DM Total column density of free electrons, or a distance estimate with ne models of the ISM.
it becomes birefringent. LCP and RCP have different refractive index : different group velocities. Rotates linearly polarized waves. λ Pulsar B A β Aristeidis Noutsos, Astronomische Gesellschaft 2010 PSR B0329+54 d β = λ2 * RM RM = π*/(λ1 –λ2 )2