Measurement of angular cross-correlation between the cosmological dispersion measure and the thermal Sunyaev--Zeldovich effect

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Main Authors: Takahashi, Ryuichi, Ioka, Kunihito, Shirasaki, Masato, Osato, Ken
Format: Preprint
Published: 2025
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author Takahashi, Ryuichi
Ioka, Kunihito
Shirasaki, Masato
Osato, Ken
author_facet Takahashi, Ryuichi
Ioka, Kunihito
Shirasaki, Masato
Osato, Ken
contents The dispersion measures (${\rm DMs}$) from fast radio bursts (FRBs) and the thermal Sunyaev--Zeldovich (tSZ) effect probe the free-electron density and pressure, respectively, in the intergalactic medium (IGM) and the intervening galaxies and clusters. Their combination enables disentangling the gas density and temperature. In this work, we present the first detection of an angular cross-correlation between the ${\rm DMs}$ and the Compton $y$ parameter of the tSZ effect. The theoretical expectation is calculated using the halo model $\texttt{HMx}$, calibrated with hydrodynamic simulations. The observational cross-correlation is measured over angular separations of $1^\prime$--$1000^\prime$ using the ${\rm DMs}$ from $133$ localized FRBs and the $y$-maps from the Planck satellite and the Atacama Cosmology Telescope (ACT). We detect a positive correlation with amplitudes of $\mathcal{A}=2.26 \pm 0.56$ ($4.0 σ$) for Planck and $\mathcal{A}=1.38 \pm 0.92$ ($1.5 σ$) for ACT, where $\mathcal{A}=1$ corresponds to the theoretical prediction of the Planck 2018 $Λ$CDM cosmology. Assuming an isothermal gas, the measured amplitude implies an average electron temperature of $\approx 2 \times 10^7 \, {\rm K}$. The correlation is highly sensitive to the matter clustering parameter $σ_8$, and its dependence on other cosmological and astrophysical parameters -- such as the ionized fraction, the Hubble constant, and baryon feedback -- differs from that of the ${\rm DM}$ alone. This suggests that future joint analyses of the ${\rm DMs}$ and the tSZ effect could help break degeneracies among these parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2511_02155
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measurement of angular cross-correlation between the cosmological dispersion measure and the thermal Sunyaev--Zeldovich effect
Takahashi, Ryuichi
Ioka, Kunihito
Shirasaki, Masato
Osato, Ken
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
The dispersion measures (${\rm DMs}$) from fast radio bursts (FRBs) and the thermal Sunyaev--Zeldovich (tSZ) effect probe the free-electron density and pressure, respectively, in the intergalactic medium (IGM) and the intervening galaxies and clusters. Their combination enables disentangling the gas density and temperature. In this work, we present the first detection of an angular cross-correlation between the ${\rm DMs}$ and the Compton $y$ parameter of the tSZ effect. The theoretical expectation is calculated using the halo model $\texttt{HMx}$, calibrated with hydrodynamic simulations. The observational cross-correlation is measured over angular separations of $1^\prime$--$1000^\prime$ using the ${\rm DMs}$ from $133$ localized FRBs and the $y$-maps from the Planck satellite and the Atacama Cosmology Telescope (ACT). We detect a positive correlation with amplitudes of $\mathcal{A}=2.26 \pm 0.56$ ($4.0 σ$) for Planck and $\mathcal{A}=1.38 \pm 0.92$ ($1.5 σ$) for ACT, where $\mathcal{A}=1$ corresponds to the theoretical prediction of the Planck 2018 $Λ$CDM cosmology. Assuming an isothermal gas, the measured amplitude implies an average electron temperature of $\approx 2 \times 10^7 \, {\rm K}$. The correlation is highly sensitive to the matter clustering parameter $σ_8$, and its dependence on other cosmological and astrophysical parameters -- such as the ionized fraction, the Hubble constant, and baryon feedback -- differs from that of the ${\rm DM}$ alone. This suggests that future joint analyses of the ${\rm DMs}$ and the tSZ effect could help break degeneracies among these parameters.
title Measurement of angular cross-correlation between the cosmological dispersion measure and the thermal Sunyaev--Zeldovich effect
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2511.02155