IUCAA Preprints
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Item Torque decay in the pulsar (p,p) diagrom effects of crustal ohmic dissipation and alignment(2001-07-05) Tauris, T. M.; Konar, SushanWe investigate the evolution of pulsars in the (P, ˙ P) diagram. We first present analytical formulae to follow the evolution of a pulsar using simple exponential models for magnetic field decay and alignment. We then compare these evolutionary tracks with detailed model calculations using ohmic decay of crustal neutron star magnetic fields. We find that, after an initial phase with a small braking index, n, pulsars evolve with enhanced torque decay (n ≫ 3) for about 1 Myr. The long term evolution depends on the impurity parameter of the crust. If impurities are negligible in older isolated pulsars we expect their true age to be approximately equal to their observed characteristic age, τ = P/(2 ˙ P). It is not possible from data to constrain model parameters of the neutron star crust.Item Magnetic field evolution of accreting neutron stars - IV effect of the curvature of space-time(2000-09-26) Konar, SushanThe evolution of the magnetic field in an accreting neutron star is investigated using a fully general relativistic treatment and assuming that initially the currents supporting the field are completely confined to the crust. We find that the field decay slows down due to the inclusion of the curvature of space-time but the final results do not differ significantly from those obtained assuming a flat space-time. We also find that such modifications are small compared to the uncertainties introduced by a lack of precise knowledge of the neutron star micro-physics.