Great Walls of Cosmic Baryons in the Northern Sky
Vikram Ravi, Kritti Sharma, and Liam Connor

TL;DR
This study maps extragalactic dispersion measure variations across the Northern sky using FRBs, revealing large-scale baryon overdensities potentially linked to cosmic structures like superclusters.
Contribution
First to create a sky map of DM variations from thousands of FRBs, identifying significant excesses associated with large-scale cosmic structures.
Findings
Detected a 150 pc cm$^{-3}$ DM excess over 30° scale near Ursa Major supercluster.
Identified a secondary DM excess near Perseus-Pisces supercluster.
Results suggest FRB DMs can trace baryon overdensities in large-scale structures.
Abstract
The dispersion measures (DMs) of fast radio bursts (FRBs) encode the total ionized-gas column densities along their sightlines. Most observed FRBs originate at distances where the cosmological principle applies. Thus, variations in the DM distribution of FRBs observed in different regions on the sky trace local sources of anisotropy, such as the warm ionized medium and circum-galactic medium of the Milky Way, and local large-scale structure. We present a map of extragalactic DM variations across the Northern sky using a few thousand FRBs from the second \chime{} catalog. We detect a excess of 150 pc cm above the global mean, extended over 30 scales and centered near , . This excess, termed Wall 1, is robust to variations in sample selection and jackknife resampling, and cannot be…
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