The influence of superfluid core cooling in the braking index of Pulsars

Pulsars are stars from which electromagnetic radiation is observed to pulsate in well-defined time intervals as the star rotates and the emission of eletromagnetic signal is located in a place different from the rotation center. The frequencies of the pulses decay with time, quantified by the braking index (n). In the canonical model n = 3, in general, for all pulsars, but observational data shows that n is lower than 3. In this work a new model is presented, based on a modification of the canonical one incorporating the influence of neutron and proton density that appear in the superfluid core and, as the star cools down, the density of the superfluid core increases making the star to shrink with time and temperature, making the inertia moment to decrease. The difference ot this model from the canonical one is that the star moment of inertia decreases with time (what would accelerate the rotation of the star) what makes the star to not slow down as fast as it should without this process. (paper)