Work

Backlighting the Universe with Fast Radio Bursts: An Anthology of Dispersion Measure Cross Correlations with Tracers of Large-scale Structure and Baryonic Matter

Year: 2026

Type: article

Abstract: Fast radio bursts (FRBs) probe baryons permeating the cosmic web through their dispersion measures (DMs), which encode the integrated electron density along cosmological sight lines. Using 3455 unique FRB sources from CHIME/FRB with ∼15′ localizations, we present an anthology of DM correlations with tracers of large-scale structure and baryonic matter at redshifts z ≲ 1.5. We measured correlations with a vector signal-to-noise ratio (SNR) of 2.4–5 with 10 probes, including galaxies (2.8), weak gravitational lensing (2.6), cosmic infrared background (4.0), cosmic microwave background (CMB) lensing (3.3), the thermal Sunyaev–Zel’dovich (tSZ) effect (3.8), X-ray emission tracing galaxy clusters (5.0) and superclusters (3.3), soft X-ray background (SXRB, 4.1), and radio continuum emission (3.0). These measurements reveal a consistent picture in which FRB sight lines intersecting overdense environments carry systematically larger DMs. Correlations with hot-gas tracers provide additional leverage on the strength of feedback, as they are strongly weighted toward the dense, bound gas. The measured amplitude of tSZ×DM and SXRB×DM correlations is consistent with theoretical predictions of baryon distribution from a DM– z relation-inferred model with moderate feedback at a ∼0.5 σ level. A weaker feedback scenario is disfavored at ∼3.5 σ by the SXRB×DM correlation under our adopted modeling assumptions. Taken together, these measurements constitute a quantitative multitracer foundation for a new era in which FRBs from next-generation facilities, such as BURSTT, CHORD, the Deep Synoptic Array, and the Square Kilometer Array, in harmony with other probes, will map the baryon content of the full extent of the cosmic web.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/ae9a79