Empirical estimates of the Galactic halo contribution to the dispersion measures of extragalactic fast radio bursts using X-ray absorption

Abstract

We provide an empirical list of the Galactic dispersion measure ($D{M}_{Gal}$) contribution to the extragalactic fast radio bursts along 72 sightlines. It is independent of any model of the Galaxy, i.e., we do not assume the density of the disk or the halo, spatial extent of the halo, baryonic mass content, or any such external constraints to measure $D{M}_{Gal}$. We use 21-cm, UV, EUV and X-ray data to account for different phases, and find that $D{M}_{Gal}$ is dominated by the hot phase probed by X-ray absorption. We improve upon the measurements of N(\oviin) and f${}_{OVII}$ compared to previous studies, thus providing a better estimate of the hot phase contribution. The median $D{M}_{Gal}$=64${}_{-23}^{+20}$ cm${}^{-3}$ pc, with a 68\% (90\%) confidence interval of 33--172 (23--660) cm${}^{-3}$ pc. The $D{M}_{Gal}$ does not appear to follow any trend with the galactic longitude or latitude, and there is a large scatter around the values predicted by simple disk+spherical halo models. Our measurements provide more complete and accurate estimates of $D{M}_{Gal}$ independent from the previous studies. We provide a table and a code to retrieve $D{M}_{Gal}$ for any FRB localized in the sky.

8 pages, 4 figures, 5 tables; accepted for publication in MNRAS

References in corpus (15)

• A bright millisecond radio burst of extragalactic origin
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The Circumgalactic Medium
• A New Electron Density Model for Estimation of Pulsar and FRB Distances
• A census of baryons in the Universe from localized fast radio bursts
• Fast Radio Bursts
• The COS-Halos Survey: Metallicities in the Low-Redshift Circumgalactic Medium
• Probing Galactic Halos with Fast Radio Bursts
• The Galactic Halo Contribution to the Dispersion Measure of Extragalactic Fast Radio Bursts
• XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Active Galactic Nuclei
• Cosmology-independent estimate of the fraction of baryon mass in the IGM from fast radio burst observations
• Exploring the dispersion measure of the Milky Way halo
• Measuring the cosmic proper distance from fast radio bursts
• Probing the structure of the gas in the Milky Way through X-ray high resolution spectroscopy
• Probing the Anisotropy of the Milky Way Gaseous Halo-II: sightline toward Mrk509

Cited by in corpus (10)

• A comparison of Galactic electron density models using PyGEDM
• The hot circumgalactic medium of the Milky Way: evidence for super-virial, virial, and sub-virial temperature, non-solar chemical composition, and non-thermal line broadening
• On the Fast Radio Burst and Persistent Radio Source Populations
• Multiwavelength observations of Fast Radio Bursts
• What it Takes to Measure Reionization with Fast Radio Bursts
• Detection of thermal Sunyaev-Zel'dovich Effect in the circumgalactic medium of low-mass galaxies -- a surprising pattern in self-similarity and baryon sufficiency
• NE2025: An Updated Electron Density Model for the Galactic Interstellar Medium
• Modeling the Cosmic Dispersion Measure in the D < 120 Mpc Local Universe
• A Sub-solar Fe/O, logT~7.5 Gas Component Permeating the Milky Way's CGM
• Constraining the Milky Way's Dispersion Measure Using FRB and X-ray Data