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A high-dynamic-range view of the growth of structure and the warm/hot Universe

Luca Di Mascolo, Tony Mroczkowski, Joshiwa van Marrewijk, Rémi Adam, Nabila Aghanim, Stefano Andreon, Eleonora Barbavara, Elia Stefano Battistelli, Esra Bulbul, Jens Chluba, Eugene Churazov, Claudia Cicone, William Coulton, Stefano Ettori, Massimo Gaspari, Ricardo Génova Santos, Matt Hilton, Adam D. Hincks, Eelco van Kampen, Tetsu Kitayama, Minju Lee, John Orlowski-Scherer, Charles Romero, Laura Salvati, Alexandro Saro, Íñigo Zubeldia

TL;DR

Understanding the growth of structure requires mapping the warm/hot ionized baryons across cosmic time, which current mm/sub-mm facilities struggle to do due to limited spectral coverage, mapping speed, and field of view. The paper advocates AtLAST—a 50 m single-dish telescope with broad spectral coverage from $30-950$ GHz, multi-band cameras (~$10^6$ detectors), and mapping speed $>10^3$—to perform a comprehensive SZ census across arcsecond-to-degree scales. It details how disentangling thermal, kinetic, and relativistic SZ signals will allow probing protoclusters at $z>2$, diffuse gas in filaments and circumgalactic halos, and measurements of non-thermal pressure and turbulence, with foreground control via multi-band data. The proposed facility would be ESO's flagship for (sub-)mm cosmology and large-scale structure, unlocking the thermal history of the Universe and informing models of galaxy evolution.

Abstract

Baryons heat to temperatures above $>\!\!10^5\,\mathrm{K}$ as they accrete onto massive overdensities -- galaxies, groups, clusters, and filaments -- where they ionize and become optically transparent. Deep mm-wave observations such as those with ALMA have begun to probe a handful ($\sim\,$4) of massive systems at $z\!\sim\!2-4$, while low-resolution mm-wave surveys have detected thousands of objects at arcminute resolution out to $z\!\approx\!2$. To truly advance the field of the evolution of large-scale structures, mapping the warm/hot distribution of ionized gas out to the redshift of their formation, the ESO community requires a large-aperture single-dish (sub-)mm telescope. This will need to provide several orders of magnitude higher mapping speeds than currently available while preserving the few arcsecond resolution required for imaging the gas and removing contaminating radio and dusty thermal signals across the full (sub-)mm wavelength range.

A high-dynamic-range view of the growth of structure and the warm/hot Universe

TL;DR

Understanding the growth of structure requires mapping the warm/hot ionized baryons across cosmic time, which current mm/sub-mm facilities struggle to do due to limited spectral coverage, mapping speed, and field of view. The paper advocates AtLAST—a 50 m single-dish telescope with broad spectral coverage from GHz, multi-band cameras (~ detectors), and mapping speed —to perform a comprehensive SZ census across arcsecond-to-degree scales. It details how disentangling thermal, kinetic, and relativistic SZ signals will allow probing protoclusters at , diffuse gas in filaments and circumgalactic halos, and measurements of non-thermal pressure and turbulence, with foreground control via multi-band data. The proposed facility would be ESO's flagship for (sub-)mm cosmology and large-scale structure, unlocking the thermal history of the Universe and informing models of galaxy evolution.

Abstract

Baryons heat to temperatures above as they accrete onto massive overdensities -- galaxies, groups, clusters, and filaments -- where they ionize and become optically transparent. Deep mm-wave observations such as those with ALMA have begun to probe a handful (4) of massive systems at , while low-resolution mm-wave surveys have detected thousands of objects at arcminute resolution out to . To truly advance the field of the evolution of large-scale structures, mapping the warm/hot distribution of ionized gas out to the redshift of their formation, the ESO community requires a large-aperture single-dish (sub-)mm telescope. This will need to provide several orders of magnitude higher mapping speeds than currently available while preserving the few arcsecond resolution required for imaging the gas and removing contaminating radio and dusty thermal signals across the full (sub-)mm wavelength range.

Paper Structure

This paper contains 2 sections, 3 figures.

Table of Contents

  1. Scientific context and motivation
  2. Technical requirements

Figures (3)

  • Figure 1: Spectral distortion from to the relativistically corrected thermal SZ effect (coloured solid lines), relativistic SZ correction for $25~\mathrm{keV}$ gas (black dashed line), and kinetic SZ effect (black dot-dashed line). In the background is a comparison of the atmospheric transmission conditions at the Chajnantor Plateau and the proposed spectral bands.
  • Figure 2: Mass-redshift detection limit for different AtLAST survey strategies DiMascolo2025 for a fixed survey time of 5 years in comparison with cluster wide-field millimeter (SZ) surveys Planck2016Bleem2023Kornoelje2025ACT2025 and the eROSITA all-sky (X-ray) survey Bulbul2024.
  • Figure 3: Simulated nearby galaxy cluster ($M_{500}\!\!=\!\!1.28\times10^{15}\,\mathrm{M_{\odot}}$, $z\!\!=\!\!0.07$; left) as observed by ALMA+ACA in Band 3 (top centre), MUSTANG-2 (bottom centre), and AtLAST at $90~\mathrm{GHz}$ (right). Adapted from Di Mascolo et al. DiMascolo2025.