Rotating Radio Transients and Their Place Among Pulsars

TL;DR

This paper reviews the discovery, properties, and classification of Rotating Radio Transients (RRATs), discussing their relation to pulsars and highlighting open questions about their nature and population.

Contribution

It clarifies the definition of RRATs, discusses their place among pulsars, and summarizes recent discoveries and open questions in the field.

Findings

RRATs are a diverse group within the pulsar population.

Many RRATs may be extreme nulling pulsars.

Open questions remain about the nature and classification of RRATs.

Abstract

Six years ago, the discovery of Rotating Radio Transients (RRATs) marked what appeared to be a new type of sparsely-emitting pulsar. Since 2006, more than 70 of these objects have been discovered in single-pulse searches of archival and new surveys. With a continual inflow of new information about the RRAT population in the form of new discoveries, multi-frequency follow-ups, coherent timing solutions, and pulse rate statistics, a view is beginning to form of the place in the pulsar population RRATs hold. Here we review the properties of neutron stars discovered through single pulse searches. We first seek to clarify the definition of the term RRAT, emphasising that "the RRAT population" encompasses several phenomenologies. A large subset of RRATs appear to represent the tail of an extended distribution of pulsar nulling fractions and activity cycles; these objects present several key open questions remaining in this field.