15 Integrated pulse profiles

Summary

Over the whole electromagnetic spectrum from radio to the very high energy gamma-rays detected by air shower telescopes, pulsars radiate beams giving pulse profiles which are unique signatures differing from pulsar to pulsar. For some individual pulsars, notably the Crab Pulsar described in Chapter 9, very similar profiles are observed over the whole spectrum. The majority of pulsars are observable only in radio; here the individual pulses are often very variable and it is by averaging the pulse shapes of many, sometimes hundreds, of pulses that the characteristic shape is seen.

The advent of the Fermi LAT satellite telescope and the air shower Cerenkov detectors HESS and VERITAS has opened a new window for observing the high-energy beamed radiation from pulsars, and the wind nebulae. Many young pulsars, and especially those with large spin-down energy, are observable with the LAT, along with many of the millisecond pulsars. In the high-energy regimes the radiation is detected as individual photons, arriving so infrequently that integration over many millions of pulse periods is needed before the profile emerges.

These integrated radio and high-energy profiles are the key to understanding the geometry and the physical processes within the magnetosphere. In this chapter we start with the radio profiles, which have provided an astonishingly wide range of phenomena, both in their detailed shapes and in their variations over various time scales.