On the long-term evolution of rotating radio transients

TL;DR

This paper models the long-term evolution of RRATs, estimating their magnetic fields and ages, and explores their evolutionary connection to other neutron star populations, suggesting RRATs are often below the pulsar death line.

Contribution

Developed a method to estimate RRATs' magnetic fields without X-ray data, linking their properties to CCOs and XDINs within a unified evolutionary framework.

Findings

RRATs have dipole fields between 7×10^9 G and 6×10^11 G.

Most RRATs are around 0.2-0.6 million years old, younger than their characteristic ages.

Many RRATs are below the pulsar death line, possibly explaining their intermittent radio bursts.

Abstract

Investigation of the long-term evolution of rotating radio transients (RRATs) is important to understand the evolutionary connections between the isolated neutron star populations in a single picture. The X-ray luminosities of RRATs (except one source) are not known. In the fallback disc model, we have developed a method to estimate the dipole field strengths of RRATs without X-ray information. We have found that RRATs could have dipole field strengths, $B_0$, at the poles ranging from $\sim 7 \times 10^9$ G to $\sim 6 \times 10^{11}$ G which fill the gap between the $B_0$ ranges of central compact objects (CCOs) and dim isolated neutron stars (XDINs) estimated in the same model. In our model, most of RRATs are evolving at ages $(\sim 2 - 6) \times 10^5$ yr, much smaller than their characteristic ages, such that, cooling luminosities of a large fraction of relatively nearby RRATs could be detected by the eROSITA all-sky survey. Many RRATs are located above the upper border of the pulsar death valley with the fields inferred from the dipole-torque formula, while they do not show strong, continuous radio pulses. The $B_0$ values estimated in our model, place all RRATs either into the death valley or below the death line. We have tentatively proposed that RRATs could be the sources below their individual death points, and their short radio bursts could be ignited by the disc-field interaction occasionally enhancing the flux of open field lines through the magnetic poles. We have also discussed the evolutionary links between CCOs, RRATs and XDINs.