Long-term evolution of RRAT J1819-1458

TL;DR

This study models the long-term evolution of RRAT J1819-1458 using the fallback disc model, successfully explaining its properties and suggesting an evolutionary link to dim isolated neutron stars.

Contribution

The paper applies the fallback disc model to RRAT J1819-1458, providing new insights into its magnetic field, evolution, and connection to other neutron star classes.

Findings

Model reproduces period, period derivative, and X-ray luminosity.

J1819-1458 has a weaker magnetic field than dipole-torque estimates.

Evolutionary link between RRATs and dim isolated neutron stars.

Abstract

At present, J1819-1458 is the only rotating radio transient (RRAT) detected in X-rays. We have studied the long-term evolution of this source in the fallback disc model. The model can reproduce the period, period derivative and X-ray luminosity of J1819-1458 simultaneously in the accretion phase at ages $\sim 2 \times 10^5$ yr. We obtained reasonable model curves with a magnetic dipole field strength $B_0 \sim 5 \times 10^{11}$ G on the pole of the neutron star, which is much weaker than the field inferred from the dipole-torque formula. With this $B_0$ and the measured period, we find J1819-1458 below and close to the radio pulsar death line. Our results are not sensitive to initial period, and the source properties can be produced with a large range of disc masses. Our simulations indicate that J1819-1458 is evolving towards the properties of dim isolated neutron stars at later phases of evolution. This implies a close evolutionary link between RRATs and dim isolated neutron stars. For other RRATs with measured period derivatives and unknown X-ray luminosities, we have estimated the lower limits on the $B_0$ values in the fallback disc model. These limits allow a dipole field distribution for RRATs that could fill the $B_0$ gap between the estimated $B_0$ ranges of dim thermal isolated neutron stars and central compact objects in the same model.