A pulsar is a highly magnetized rotating neutron star that emits beams of radiation through its magnetic poles, in the direction of the Earth. This makes it seem to pulse, as seen from Earth. There likely are similar objects that pulse as seen from other directions, but not from Earth. Can we tell the difference between one of these objects and an ordinary neutron star?

Is there any way of detecting pulsars that are not pulsing in our direction?


1 Answer 1


They don't need to be pointed exactly at us, since the angular beam radius is a few degrees (Pulsar Astronomy, P. 212) but there is a portion that we can't detect, described by a beaming factor (P. 211):

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The larger beamwidth at higher energies can be seen in these graphs:

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R. N. Manchester

We mostly can't see "ordinary neutron stars". "neutron stars can only be easily detected in certain instances, such as if they are a pulsar or part of a binary system" - Wikipedia

If the pulsar is radiating gamma rays more isotropically (but still varying with phase as in the Manchester charts), then these could be detected.

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    $\begingroup$ So even if we manage to detect a neutron star, if the beam isn't roughly pointed towards us, there is no way of knowing that it is a pulsar. $\endgroup$
    – usernumber
    Commented Dec 19, 2019 at 9:09
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    $\begingroup$ @usernumber This might be an example: "For Geminga, astronomers view the bright gamma-ray pulses along the edge of the torus, but the radio beams near the jets point off to the sides and remain unseen" $\endgroup$ Commented Dec 19, 2019 at 18:08
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    $\begingroup$ @usernumber New article about Geminga. $\endgroup$ Commented Dec 20, 2019 at 4:45
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    $\begingroup$ This is actually avoiding the question. I take it your answer is no? $\endgroup$
    – ProfRob
    Commented Jan 29, 2020 at 11:04

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