Revisiting Pulsar Velocities Using Gaia Data Release 2

TL;DR

This study uses Gaia DR2 data to measure pulsar velocities, revealing insights into neutron star kicks, binary evolution, and the importance of local stellar motions in understanding pulsar dynamics.

Contribution

It provides new measurements of pulsar velocities using Gaia DR2, highlighting the significance of local stellar motions and the velocity dispersion in understanding neutron star origins.

Findings

Median velocity difference between LSRs and Galactic rotation is ~7.6 km/s.

Velocity dispersion among local stellar groups is ~27.5 km/s.

Transverse velocity of double neutron star system J0737-3039A/B is measured as 26 km/s.

Abstract

Precise measurements of neutron star (NS) velocities provide critical clues to the supernova physics and evolution of binary systems. Based on Gaia Data Release 2 (DR2), we selected a sample of 24 young (<3 Myr) pulsars with precise parallax measurements and measured the velocity of their local standard of rest (LSR) and the velocity dispersion among their respective local stellar groups. The median velocity difference between thus calculated LSRs and the Galactic rotation model is ~7.6km/s, small compared to the typical velocity dispersion of ~27.5km/s. For pulsars off the Galactic plane, such differences grow significantly to as large as ~40 km/s. More importantly, the velocity dispersion of stars in the local group of low-velocity pulsars can be comparable to their transverse velocities, suggesting that the intrinsic velocities of NS progenitors should be taken into account when we consider their natal kicks and binary evolution. We also examined the double NS systems J0737- 3039A/B, and measured its transverse velocity to be 26(+18, -13) km/s assuming nearby Gaia sources being representative of its birth environment. This work demonstrated the feasibility and importance of using Gaia data to study the velocity of individual systems and velocity distribution of NSs.