Measuring the Variance of the Macquart Relation in z-DM Modeling

Understand

The Macquart relation describes the correlation between the dispersion measure (DM) of fast radio bursts (FRBs) and the redshift $z$ of their host galaxies.

• The scatter of the Macquart relation is sensitive to the distribution of baryons in the intergalactic medium (IGM) including those ejected from galactic halos through feedback processes.
• The width of the distribution in DMs from the cosmic web (${\rm DM}_{\rm cosmic}$) is parameterized by a fluctuation parameter $F$, which is related to the cosmic DM variance by $\sigma_{\rm DM}= F z^{-0.5}$.
• In this work, we present a new measurement of $F$ using 78 FRBs of which 21 have been localized to host galaxies.