Evolution of the long-period pulsar PSR J0901−4046

Abstract

ABSTRACT The fallback disc model predicted that anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) will evolve to isolated long-period pulsars (LPPs) before the discovery of the first two LPPs this year. Unlike normal radio pulsars, LPPs show transient pulsed-radio epochs with unusual and variable pulse shapes, similar to the radio behaviour of the few radio emitting AXP/SGRs. We show that the present properties of the recently discovered second LPP, PSR J0901−4046 (P ≃ 76 s), are obtained as a result of evolution in interaction with a fallback disc, as we had already shown for the first discovered LPP, GLEAM-X J162759.5−523504.3 (P ≃ 1091 s). While there is only an upper limit to the period derivative, $\dot{P}$, of GLEAM-X J162759.5−523504.3, the $\dot{P}$ of the PSR J0901−4046 has already been measured, providing better constraints for the evolutionary models. The model can produce the source properties with a dipole moment μ ≃ 1030 G cm3. The results are not sensitive to the initial pulsar period. Our results indicate that PSR J0901−4046 went through an AXP/SGR epoch at an age of a few 104 yr, and is ∼(6–8) × 105 yr old at present.