Characterizing Pulsar Distances Using HI Kinematics

TL;DR

This paper derives pulsar distances using HI kinematics with an advanced Galactic rotation model, providing results and software that are consistent with parallaxes and electron density models.

Contribution

It introduces updated kinematic distance estimates for 66 pulsars using a modern Galactic rotation curve and shares the software publicly.

Findings

Kinematic distances differ by less than 1 sigma from parallaxes for most pulsars.

Results are generally consistent with the NE2025 electron density model.

The study provides an online repository with data and software.

Abstract

Distance measurements are fundamental to radio pulsars' use as astrophysical probes of General Relativity and the interstellar medium. One of the primary methods for determining pulsar distances is HI kinematics, which leverages the radial velocities of HI absorption and emission features detected along pulsar lines-of-sight. This method necessarily assumes a model for Galactic rotation, our knowledge of which continues to evolve in both accuracy and precision. In this research note, we derive kinematic distances for 66 pulsars with archival HI radial velocity measurements using a state-of-the-art Galactic rotation curve. The results and software are provided in an online repository. Our kinematic distances differ by $<1\sigma$ from published parallaxes for nearly all pulsars in the sample that have both types of distance measurement available. Comparison to the NE2025 Galactic electron density model shows general consistency between measured and predicted distances.