The Crucial First Step in the Discovery of Millisecond Pulsars

TL;DR

This paper recounts the first discovery of millisecond pulsars through interplanetary scintillation detection in radio source 4C 21.53, highlighting its significance for astronomy and cosmology, especially in gravitational wave research.

Contribution

It provides a first-hand account of the initial discovery process of millisecond pulsars, a crucial step that is rarely documented in detail.

Findings

Discovery of millisecond pulses from 4C 21.53

Significance of interplanetary scintillation in pulsar detection

Implications for gravitational wave background studies

Abstract

Millisecond pulsars, like pulsars, have led to major advances in many areas of astronomy and physics. The discovery in 2023 of a cosmological gravitational wave (GW) stochastic background using millisecond pulsar timing arrays has focused attention on the importance of millisecond pulsars, to both multi-messenger astronomy and cosmology, and for identifying the origin of the GW stochastic background, which is hypothesized to be due to supermassive black hole binaries (SMBHBs). Unlike pulsars, however, for which the details of the discovery are well-known, those of millisecond pulsars are not well known. In particular, the details of the first crucial step in the discovery of millisecond pulsars, namely the discovery of interplanetary scintillation (IPS) in the radio source 4C 21.53, are known only to the author. This article presents a first-hand account of this crucial first step, which resulted ultimately in the discovery of millisecond pulses from this object. A brief description of interplanetary and interstellar scintillation and scattering is given in the Appendix.