On The Braking Index Of Binary Pulsars

Pulsars are neutron stars spinning rapidly. The extreme characters of them such as high density, high temperature, high magnetic field and high speed rotation, can help us understand the physical composition of the compact stars. The precision measurement of the time arriving of the pulsars in binary system allows us to get clear insight of general relativity and the different predictions given by different gravitational theories. This thesis is mainly on the abnormity of the braking index of the pulsar in binary systems. The observation shows that the breaking indexes in binary systems are much larger than those of single pulsars. We think the time residual from Doppler residual effect in pulsar binary system can influence the first-order derivative and second derivative of pulsar, thus making the braking index much greater than 3. The investigation is significant in the studying the theories of pulsars. Knowing the mechanism of the spin-down of the pulsars allows us to have a better understanding of the residual of the pulsar's time of arriving, thus creating a better foundation for testing the gravitational waves and pulsar navigating by using pulsar's time arriving. The paper is divided into six parts.The chapter one is mainly about the pulsar and its basic problems. It includes the inner structure, the equation of state and the relation between mass and radius of the pulsars. At the end, an introduction about the typical radiative regions of the pulsar is introduced.Chapter two introduces the braking index of pulsars, discussing about the origin of pulsar' energy and spinning down. According to the model of magnetic dipole radiation, the braking index is 3. However, the braking index of pulsars are far bigger than 3 in most cases, according to the standand observed first derivative and second derivative of spin frequency.Chapter three introduces some timing models in binaries and Tempo2. The signal received by an observer has time quasi-periodic residuals in most cases.In chapter four, the braking index of 21 pulsars in binary system are studied. By introducing the contribution in the Doppler residual effect of pulsar in binaries, the first order derivative of spinning frequency will decrease, thus the braking index of these pulsars can be reduced in a large scale. The result is that the braking index in the most sources of these 21 binaries are reduced to 3 or decrease for 4 or 5 order of magnitude. In the meantime, the spin-orbit coupling model and the companion induced orbit precession model are considered to improve the Doppler residual effect.In chapter five, Doppler residual effect is implanted into Tempo2. When the change of first order derivative induced by Doppler residual effect is in acting, the time residual under Doppler residual effect is obtained, two time residual with or without Doppler residual effect can be compared. In the case of the time residual from two sources is small or close to the time residual without Doppler residual effect. At the same time, the braking index is normal.Chapter six is summary and expectation, which contains that the Doppler residual effect has an effect on TOA of pulsar in binary systems and the interpretation about the anomaly on braking index of the 21 sources, and the braking index of the 2 sources with observed data become normal value in Tempo2.