The effect of kick velocities on the spatial distribution of millisecond pulsars and implications for the Galactic center excess

Abstract

Recently it has become apparent that the Galactic center excess (GCE) is spatially correlated with the stellar distribution in the Galactic bulge. This has given extra motivation for the unresolved population of millisecond pulsars (MSPs) explanation for the GCE. However, in the "recycling" channel the neutron star forms from a core collapse supernovae that undergoes a random "kick" due to the asymmetry of the explosion. This would imply a smoothing out of the spatial distribution of the MSPs. We use N-body simulations to model how the MSP spatial distribution changes. We estimate the probability distribution of natal kick velocities using the resolved gamma-ray MSP proper motions, where MSPs have random velocities relative to the circular motion with a scale parameter of 77+/-6 km/s. We find that, due to the natal kicks, there is an approximately 10% increase in each of the bulge MSP spatial distribution dimensions and also the bulge MSP distribution becomes less boxy but is still far from being spherical.

21+10 pages, 11+12 figures. V2: added references and minor typo corrected. V3: reflects JCAP accepted version

References in corpus (9)

• The Structure of the Milky Way's Bar Outside the Bulge
• The observed velocity distribution of young pulsars
• Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
• NMAGIC: Fast Parallel Implementation of a Chi-Squared-Made-to-Measure Algorithm for Modelling Observational Data
• The characteristics of the Galactic center excess measured with 11 years of Fermi-LAT data
• The birth properties of Galactic millisecond radio pulsars
• Comparing the Galactic Bulge and Galactic Disk Millisecond Pulsars
• Cherenkov Telescope Array sensitivity to the putative millisecond pulsar population responsible for the Galactic center excess
• Inverse Compton emission from millisecond pulsars in the Galactic bulge

Cited by in corpus (3)

• Millisecond Pulsars from Accretion Induced Collapse as the Origin of the Galactic Centre Gamma-ray Excess Signal
• Millisecond Pulsar Kicks Cause Difficulties in Explaining the Galactic Center Gamma-Ray Excess
• Applying Simulation-Based Inference to Spectral and Spatial Information from the Galactic Center Gamma-Ray Excess