# Pulsar beam radiant intensity distribution

I'm curious about the radiant intensity distribution of pulsars: what's the general dependence of intensity on angle, and what are typical angular beam widths? How much does the beam width vary between pulsars? (Presumably this is tied to magnetic field strength.)

Even something as simple as a very sketchy plot of intensity vs. angle would be great. It's easy enough to find plots of observed intensity vs. time for individual pulsars, but it takes a bit to get from those to the distribution at the source.

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## 1 Answer

My incomplete understanding is that the width of pulsars generally seems to depend on their periods and the angle between their magnetic axes and rotational axes. The general trend is for shorter period pulsars to have pulse widths that are a larger fraction of their periods. See On the pulse-width statistics in radio pulsars for some more detail. It looks like there are pulse half widths as narrow as a few degrees (~1/100 of a period), and some that are as wide as ninety degrees (1/4 of a period, meaning that if we were able to see both pulsing sides, the pulsar is on ~1/2 the time).

Given that level of variation, I'm not sure if there is a very general sort of plot of intensity versus phase. Some are nicely Gaussian pulses, with a nice interpulse at 180 degree phase separation, whereas others have much more structure. Take a look at some of the figure in Multi-frequency integrated profiles of pulsars (there are a total of 34 pulsar profiles plotted, and it should be available to all as it was posted to arXiv).

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Thanks for finding this after all this time! I don't mind there not being a general form of the plot; the figures in that paper give me a pretty good idea of the kinds of things that exist. I'll give those papers a skim at some point and see if I have any follow-up questions before I accept. –  Jefromi Feb 5 '12 at 3:46
I only recently became active here, and I happened to notice that some of the unanswered questions were things that I could answer, or knew references with good answers. Your question happened to one that I thought was interesting. –  jdmcbr Feb 5 '12 at 6:24
Did you happen to get a chance to look this over? –  jdmcbr Feb 29 '12 at 3:39
I did, sorry! Thanks again! –  Jefromi Feb 29 '12 at 3:44
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