Pulsars & Millisecond Pulsars: Observation, Measurement & Evidence

A pulsar contains a rapidly rotating neutron star with a magnetic axis generally tilted relative to its rotation axis. Charged particles accelerated in the magnetosphere produce radio, optical, X-ray, or gamma-ray emission in beams tied to the magnetic geometry.

Pulse arrival times reveal periods stable enough for precision timing experiments. Measured spin-down rates imply energy loss, binary pulsars trace relativistic orbital effects, and millisecond pulsars cluster strongly in systems with histories of binary interaction.

Conservation of angular momentum makes a collapsed stellar core rotate rapidly, while magnetic flux compression greatly strengthens the field. Rotational energy powers magnetospheric particle acceleration and radiation. Over time isolated pulsars spin down; in close binaries, accretion can transfer angular momentum and recycle an old neutron star into a millisecond pulsar.

Pulse arrival times can be predicted to extraordinary precision. Timing reveals binary companions, spin-down, glitches, dispersion through interstellar plasma, and relativistic orbital effects.