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arXiv · 2510.08331

The superclustering of hot gas: cosmological sensitivity in the Websky simulations

M. Lokken·J. R. Bond·R. Hložek·N. J. Carlson·Z. Li·A. van Engelen
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Abstract

Combinations of galaxy surveys and cosmic microwave background secondaries, such as the thermal Sunyaev-Zel'dovich (tSZ) effect, are increasingly being used to jointly constrain cosmology and astrophysical properties of the gas within and beyond halos. Standard cross-correlations measure a directionless correlation between the microwave maps and galaxy catalogs. However, more information about the cosmic web structure can be captured by summary statistics which include environmental constraints and measure oriented correlations along axes of structure, such as filaments or superclusters. This work studies the sensitivity of multipole moments of constrained oriented stacks, a directional and environmentally-dependent statistic, to variations in cosmological and astrophysical parameters. We run nine different 2.4 Gpc-per-side simulations with the Websky algorithm, varying the matter density within flat $Λ$CDM, and create mock tSZ maps with each. We also apply six different gas prescriptions, imitating AGN feedback variations, to the fiducial cosmology. We analyze oriented stacks of the tSZ signal in supercluster regions in each simulation, focusing on signal out to $\sim20$ transverse Mpc from massive ($M>5\times10^{13}~M_\odot$) halos. The cosmology variations affect anisotropic and isotropic measurements similarly, while the halo-pasted gas variations mostly affect the isotropic signal. Our results suggest it is worthwhile to incorporate directional information into SZ-galaxy cross-correlations to increase cosmological sensitivity and help break degeneracies with gas physics.

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M. Lokken, J. R. Bond, R. Hložek, N. J. Carlson, Z. Li, A. van Engelen. 2026-06-02. The superclustering of hot gas: cosmological sensitivity in the Websky simulations. https://doi.org/10.1088/1475-7516%2F2026%2F05%2F011

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