Evolutionary tracks of millisecond pulsars with low-mass companions

TL;DR

This paper models the evolution of millisecond pulsars with low-mass companions, explaining diverse observed systems and predicting possible transitions between different binary states over hundreds of millions of years.

Contribution

It introduces a new evolutionary model that accounts for various black widow pulsar systems and their potential transition to low-mass X-ray binaries.

Findings

Ablation phase lasts a few hundred million years.

Many black widow systems can be explained by this ablation process.

Some systems may re-establish Roche lobe contact and become LMXBs.

Abstract

We consider the evolution of millisecond radio pulsars in binary systems with a main-sequence or evolved stellar companion. Evolution of non-accreting binary systems with "eclipsing" milisecond pulsars was described by Klu\'zniak, Czerny & Ray (1992) who predicted that systems like the one containing the Terzan 5 PSR 1744-24A will in the future become accreting low mass X-ray binaries (LMXBs), while PSR 1957+20 may evaporate its companion. The model presented in the current paper gives similar results for these two objects and allows to obtain diverse evolutionary tracks of millisecond pulsars with low mass companions (black widows). Our results suggest that the properties of many black widow systems can be explained by an ablation phase lasting a few hundred million years. Some of these sources may regain Roche lobe contact in a comparable time, and become LMXBs.