Modeling the Spatial Distribution of Neutron Stars in the Galaxy

TL;DR

This study models the spatial and velocity distributions of old neutron stars in the Milky Way using Monte Carlo simulations, revealing their large radial spread and vertical distribution characteristics.

Contribution

It introduces a comprehensive simulation framework for neutron star distributions considering complex initial velocities and spatial profiles, advancing understanding of their Galactic dynamics.

Findings

Neutron stars have a large radial distribution close to their progenitors.

Vertical distribution of neutron stars follows a double exponential profile.

Radial and vertical distributions are correlated and vary with galactic radius.

Abstract

In this paper we investigate the space and velocity distributions of old neutron stars (aged 109 to 1010 yr) in our Galaxy. Galactic old Neutron Stars (NSs) population fills a torus-like area extending to a few tens kiloparsecs above the galactic plane. The initial velocity distribution of NSs is not well known, in this work we adopt a three component initial distribution, as given by the contribution of kick velocities, circular velocities and Maxwellian velocities. For the spatial initial distribution we use a Gamma function. We then use Monte Carlo simulations to follow the evolution of the NSs under the influence of the Paczy{\P}nski Galactic gravitational potential. Our calculations show that NS orbits have a very large Galactic radial expansion and that their radial distribution peak is quite close to their progenitors' one. We also study the NS vertical distribution and find that it can well be described by a double exponential low. Finally, we investigate the correlation of the vertical and radial distribution and study the radial dependence of scale-heights.