On the spin period distribution of millisecond pulsars

TL;DR

This study analyzes the spin period distribution of millisecond pulsars using multiple samples, finding a Weibull distribution fits well and predicting limited discovery of sub-millisecond pulsars with future surveys.

Contribution

It provides the first comprehensive analysis of MSP spin distributions across different environments and corrects for observational biases, revealing no significant differences among subpopulations.

Findings

All samples fit a Weibull distribution of spin frequencies.

No significant difference in spin distribution among subpopulations.

Sub-millisecond pulsars are unlikely to be discovered by the Square Kilometer Array.

Abstract

Spin period distribution provides important clues to understand the formation of millisecond pulsars (MSPs). To uncover the intrinsic period distribution, we analyze three samples of radio MSPs in the Galactic field and in globular clusters. The selection bias due to pulse broadening has been corrected but turns out to be negligible. We find that all the samples can be well described by a Weibull distribution of spin frequencies. Considering MSPs in the Galactic field or in globular clusters, and in isolation or in binary systems, we find no significant difference in the spin distribution among these subpopulations. Based on the current known population of MSPs, we find that sub-millisecond pulsars are unlikely to be discovered by the Square Kilometer Array, although up to $\sim10$ discoveries of pulsars that spin faster than the current record holder of $P=1.4$~ms are expected.