Probing Milky Way's hot gas halo density distribution using the dispersion measure of pulsars

TL;DR

This study investigates the density distribution of the Milky Way's hot gas halo using pulsar dispersion measures, finding that certain models are consistent with observations while others are not, which informs our understanding of galactic baryon content.

Contribution

It compares different theoretical models of the hot gas halo's density distribution against pulsar data to constrain the halo's structure and baryon content.

Findings

NFW model is inconsistent with pulsar data.

MB and FHG models fit the observed dispersion measures.

Supports the hot gas halo as a significant baryon reservoir.

Abstract

A number of recent studies indicates a significant amount of ionized gas in a form of the hot gas halo around the Milky Way. The halo extends over the region of 100 kpc and may be acountable for the missing baryon mass. In this paper we calculate the contribution of the proposed halo to the dispersion measure (DM) of the pulsars. The Navarro, Frenk & White (NFW), Maller & Bullock (MB) and Feldmann, Hooper & Gnedin (FHG) density distibutions are considered for the gas halo. The data set includes pulsars with the distance known independently from the DM, e.g. pulsars in globular clusters, LMC, SMC and pulsars with known parallax. The results exclude the NFW distribution for the hot gas, while the more realistic MB and FHG models are compatible with the observed dispersion measure.