A decade of transitional millisecond pulsars

TL;DR

This review summarizes ten years of research on transitional millisecond pulsars, systems that switch between accretion and radio pulsar states, shedding light on neutron star spin-up processes.

Contribution

It provides a comprehensive overview of observational campaigns and advances in understanding tMSPs over the past decade.

Findings

Identification of three confirmed tMSPs and one candidate.

Multi-wavelength campaigns have revealed key physical processes.

Insights into neutron star recycling mechanisms.

Abstract

Transitional millisecond pulsars (tMSPs), which are systems that harbor a pulsar in the throes of the recycling process, have emerged as a new source class since the discovery of the first such system a decade ago. These systems switch between accretion-powered low-mass X-ray binary (LMXB) and rotation-powered radio millisecond pulsar (RMSP) states, and provide exciting avenues to understand the physical processes that spin-up neutron stars to millisecond periods. During the last decade, three tMSPs, as well as a candidate source, have been extensively probed using systematic, multi-wavelength campaigns. Here we review the observational highlights from these campaigns and our general understanding of tMSPs.