Implications of Radio Pulsar Crust Size on its Braking Index : Current School News

Implications of Radio Pulsar Crust Size on its Braking Index

Implications of Radio Pulsar Crust Size on its Braking Index.


There are several obvious observable evolutionary evidences among all the population of known pulsars, but a consistent description of this evolutionary trend is generally lacking in the literature. In this study,

we provide a consistent interpretation of this evolutionary effect, on the ground that the exchange of moment of inertia with time between superiud component and the solid crust component as the temperature of the neutron star drops is a signicant process of energy loss in the star.

This process of rotational energy loss, powers magnetic eld growth in young pulsars and the inverse of this process is responsible for magnetic eld decay in older pulsars.

Based on this premise we were able to account for the observed rst deceleration parameter and second deceleration parameter of the pulsars with signicant determination of their spin down parameters. The value of the observed braking index for each pulsar is an indicator of its crust size. 


Pulsars are highly magnetized, rapidly rotating neutron stars that appear as giant cosmic lighthouse. While radio pulsars are those that emit most of its radiation in radio wavelength and are powered by loss of rotational kinetic energy of the star Goldreich & Julian (1969).

They are observed only when the pulsed electromagnetic radiation from it sweeps across the line of sight of the observer on the earth’s surface.

The word pulsar is a contraction of pulsating starand it rst appeared in print in 1968 Hewish et al. (1968). Pulsars originate when an old, massive star explodes as a supernova.

The core collapses through the white dwarf stage till its constituent protons and electrons combine to form neutrons. The electromagnetic emission from pulsars comes at the expense of a loss of rotational energy, which cause its rate of rotation to decrease, or spin down.

The spin down rate is only about a millionth of a second over 100 years. Pulsars are relatively too small, but very dense to order of 1014gcm?. They have extremely strong magnetic eld, which creates a hot spot above each magnetic pole.

It also produces an intense beam of radiation that is strongest at radio wavelength. The magnetic eld axis is offset from the rotation (spin) axis. Hence if the pulsar is oriented suitably, the beam can shine in our direction, as the pulsar spins.

We detect a pulse of radio waves each time the beam ashes the radio telescope. But as pulsar ages and slows down, their magnetic eld strength weakens and they stop producing detectable beam. Hence all pulsars are neutron stars, but not all neutron stars are pulsars (this has been discussed further in chapter two).

First pulsar was discovered in 1967 by Jocelyn-Bell (later Jocelyn-Bell Burnell) and Antony Hewish of the University of Cambridge, UK, during their study of radio scintillations caused by interstellar plasma Hewish et al. (1968).


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