Detection of the Cosmological 21 cm Signal in Autocorrelation at z ∼ 1 with the Canadian Hydrogen Intensity Mapping Experiment
Year: 2026
Type: article
Abstract: We present the first detection of the cosmological 21 cm intensity mapping signal in autocorrelation at z ∼ 1 with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Using 94 nights of observation, we have measured the 21 cm auto power spectrum over a frequency range of 608.2–707.8 MHz ( z = 1.34–1.01) at 0.4 h Mpc −1 ≲ k ≲ 1.5 h Mpc −1 , with a detection significance of 12.4 σ . Our analysis employs significant improvements to the CHIME data processing pipeline compared to previous work, including novel radio frequency interference detection and masking algorithms, achromatic beamforming techniques, and foreground filtering before time averaging to minimize spectral leakage. We establish the robustness and reliability of our detection through a comprehensive suite of validation tests. We also measure the 21 cm signal in two independent sub-bands centered at z ∼ 1.08 and z ∼ 1.24 with detection significance of 8.6 σ and 9.1 σ , respectively. We briefly discuss the theoretical interpretation of these measurements in terms of a power spectrum model, deferring the details to a companion paper. This auto power spectrum detection demonstrates CHIME’s capability to probe large-scale structure through 21 cm intensity mapping without reliance on external galaxy surveys.
Source: The Astrophysical Journal
Authors: Mandana Amiri, Kevin Bandura, Arnab Chakraborty, Jean-François Cliche, Matt Dobbs, Simon Foreman, Liam Gray, Mark Halpern, Alex S Hill, Gary Hinshaw, Carolin Höfer, Albin Joseph, Nolan Kruger, T. L. Landecker, Rik van Lieshout, Joshua MacEachern, Kiyoshi W. Masui, Juan Mena-Parra, Kyle Miller, Nikola Milutinovic, Arash Mirhosseini, Laura Newburgh, Anna Ordog, Ue-Li Pen, Tristan Pinsonneault-Marotte, Alex Reda, Andre Renard, Kana Sakaguri, J. Richard Shaw, Shabbir Shaikh, Seth R. Siegel, Saurabh Singh, David Spear, Yukari Uchibori, Keith Vanderlinde, Haochen Wang, Donald V. Wiebe, Dallas Wulf
Institutions: University of British Columbia, West Virginia University, McGill University, Arizona State University, Herzberg Institute of Astrophysics, University of British Columbia, Okanagan Campus, University of Groningen, Canadian Institute for Theoretical Astrophysics, Netherlands Institute for Radio Astronomy, Massachusetts Institute of Technology, University of Toronto, Yale University, Western University, Canadian Institute for Advanced Research, Institute of Astronomy and Astrophysics, Academia Sinica, Perimeter Institute, SLAC National Accelerator Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, SKA Observatory, Raman Research Institute
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, U.S. Department of Energy, Alfred P. Sloan Foundation, Arizona State University, Canadian Institute for Advanced Research, University of Utah, McGill University, Western Canada Research Grid, Government of Canada, Industry Canada, University of Toronto, Alliance de recherche numérique du Canada, Institut Périmètre de physique théorique, Office of Science, Smithsonian Astrophysical Observatory, Natural Sciences and Engineering Research Council of Canada, National Research Council Canada, Fonds de recherche du Québec – Nature et technologies
Awards: Collaborative Research: Cosmology with CHIME, Collaborative Research: Mapping the universe in neutral hydrogen with CHIME, Collaborative Research: Cosmology with CHIME, G449004537, Collaborative Research: Mapping the universe in neutral hydrogen with CHIME, Collaborative Research: Mapping the universe in neutral hydrogen with CHIME, G4998900716, G5501962367, G6304299314, Collaborative Research: Cosmology with CHIME, G78629346, G832689143, Collaborative Research: Mapping the universe in neutral hydrogen with CHIME
OpenAlex ID: W7214581596