Evolution of isolated neutron stars based on the T-tSNR age discrepancy problem

Many studies has been made on the nature and the evolution of magnetic fields of isolated neutron stars while it is not possible to reach such high magnetic fields in laboratories. Radio pulsars have magnetic fields on the order of magnitude 10^12-10^13 G while magnetars have higher magnetic fields on the order of magnitude 10^14-10^15 G. That is why it is an important question to find out the physics of such high magnetic fields, especially in astrophysics. We discuss this problem in relation to isolated pulsars which are physically connected to SNRs. We examine the evolution of a sample of isolated X-ray and/or radio pulsars for which there are huge differences between the characteristic pulsar ages and the measured supernova ages which they are physically connected to. Based on a previous work by Ankay et al. [8] on the X-ray pulsar 1E 1207.4-5209 we show that there are some other young isolated X-ray pulsars which show B-decay as the predominant effect throughout their evolution. As compared to ordinary radio pulsars the magnetodipole radiation torques are not so effective for such pulsars and the characteristic decay times are significantly shorter (about 3 orders of magnitude). We propose simple evolutionary tracks and possible physical interpretations for this new class of neutron stars.