Firstly I thought that Pulsars are rapidly rotating, highly magnetic compact stars. The rotating magnetic field of a pulsar acts as a generator, accelerating energetic charged particles that then stream along the field lines”. At a glance the answer looks quite decent but second look does not convinces me. First important thing how are these magnetic fields are formed? For a electrically charged particles moving in a ring generates a magnetic field but the particles in neutron stars are neutrons which are electrically neutral. Then a second one was the equations which are involved in it, when protons collide with electrons during the formation of neutron star they form neutrons and give out neutrino, to what I have learnt, the equation does not feels good as when a neutron gets converted into a proton by beta decay an electron and an anti-neutrino is emitted so if we reverse this in time a proton, electron and anti-neutrino forms a neutron which is different from the previous equation, why are there two sets of equations for this?


welcome in the stack-community. Here are my proposed answers:

$\mathrm{I}.$ A pulsar is a neutron star that is mostly made up of neutrons. On the surface, gravitational pressure does not hinder the $\beta^{-}$ decay of neutrons, and so charged particles such as electrons and protons can form a magnetic field due to the whirling rotation of these objects. The small size and the high angular momentum create enormous magnetic fields capable of "tapering" the atoms.

$\mathrm{II.}$ It is not correct to say that electrons collide on protons, during the gravitational collapse. More precisely, due to the gravitational pressure, a $\beta$-inverse decay is triggered, which can be written as: $$ \bar{\nu}_{e} + p \rightarrow n + e^+$$ i.e. electronic anti-neutrino, $\bar{\nu}_e$, and a proton, p, exchange a $W^+$ virtual boson, and produce a neutron plus a positron. This positrons then collide with the free elctrons in the star during the collapsing and emits photons: $$e^-+e^+\rightarrow 2\gamma$$

P.s. Thanks to @Triatticus for the corrections to the photons counting in the electron-positron annihilation.

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    $\begingroup$ Should be $e^+ + e^- \rightarrow \gamma + \gamma$ $\endgroup$ – Triatticus Jan 13 at 18:29
  • $\begingroup$ Yes @Triatticus, you are right. Just a bad typo, i'll edit. $\endgroup$ – Andrea Mosena Jan 13 at 19:11
  • $\begingroup$ Thank you so much sir. $\endgroup$ – PRIYANSHU Jan 14 at 3:36

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