2.2 Pulse Profiles 

Pulsars are weak radio sources. Mean flux densities, usually quoted in the literature at a radio frequency of 400 MHz, vary between 1 and 100 mJy (1 Jy ). This means that the addition of many thousands of pulses is required in order to produce a discernible profile. A remarkable fact is that, although the individual pulses vary quite dramatically from pulse to pulse, at any particular observing frequency the integrated profile is very stable. The pulse profile can thus be thought of as a finger print of the emission beam.

  

Figure 2: Single pulses from PSR B0329+54. Click here to see the movie in action.

This process is demonstrated in the animation shown in Fig.  2 -- a sequence of consecutive single pulses for one of the brightest pulsars PSR B0329+54 . This pulsar is seen in the animation to stabilise into its characteristic 3-component form after the summation of about 10 seemingly erratic single pulses. This property is of key importance in pulsar timing measurements (§ 4).

A sample of pulse profiles is presented in Fig.  3 in which a great diversity in profile morphology can be seen.

  

Figure 3: A variety of integrated pulse profiles taken from the available literature. References: (a,b,d,f: [66]); (c: [23]); (e,g,i: [90]); (h: [28]). Each profile represents 360 degrees of rotational phase. These, and over 2600 other pulse profiles are available on-line [3].

Binary and Millisecond Pulsars D. R. Lorimer (dunc@mpifr-bonn.mpg.de) http://www.livingreviews.org/lrr-1998-10 © Max-Planck-Gesellschaft. ISSN 1433-8351 Problems/Comments to livrev@aei-potsdam.mpg.de