The Atacama Cosmology Telescope: Large-scale velocity reconstruction with the kinematic Sunyaev-Zel'dovich effect and DESI LRGs

Abstract The kinematic Sunyaev-Zel'dovich (kSZ) effect induces a non-zero density-density-temperature bispectrum, which we can use to reconstruct the large-scale velocity field from a combination of cosmic microwave background (CMB) and galaxy density measurements, in a procedure known as “kSZ velocity reconstruction”. This method has been forecast to constrain large-scale modes with future galaxy and CMB surveys, improving their measurement beyond what is possible with the galaxy surveys alone. Such measurements will enable tighter constraints on large-scale signals such as primordial non-Gaussianity, deviations from homogeneity, and modified gravity. In this work, we demonstrate a statistically significant measurement of kSZ velocity reconstruction for the first time, by applying quadratic estimators to the combination of the ACT DR6 CMB+kSZ map and the DESI LRG galaxies (with photometric redshifts) in order to reconstruct the velocity field. We do so using a formalism appropriate for the 2-dimensional projected galaxy fields that we use, which naturally incorporates the curved-sky effects important on the largest scales. We find evidence for the signal by cross-correlating with an external estimate of the velocity field from the spectroscopic BOSS survey and rejecting the null (no-kSZ) hypothesis at 3.8σ. Our work presents a first step towards the use of this observable for cosmological analyses.

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Publication Details

Journal
Journal of Cosmology and Astroparticle Physics
Published
2025-05-01
DOI
https://doi.org/10.1088/1475-7516/2025/05/057
Citations
6
Primary Topic
Cosmology and Gravitation Theories
Type
article
Field-Weighted Citation Impact
6.93

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article

The Atacama Cosmology Telescope: Large-scale velocity reconstruction with the kinematic Sunyaev-Zel'dovich effect and DESI LRGs

Matthew C. Johnson, Sigurd Næss, Frank J. Qu, Aleksandra Kusiak et al.
6 citations
Journal of Cosmology and Astroparticle Physics
Cosmology and Gravitation Theories
6.93
article

The Atacama Cosmology Telescope: Large-scale velocity reconstruction with the kinematic Sunyaev-Zel'dovich effect and DESI LRGs

Matthew C. Johnson, Sigurd Næss, Frank J. Qu, Aleksandra Kusiak, Fiona McCarthy, Kavilan Moodley, Jo Dunkley, J. Richard Bond, Hongbo Cai, Simone Ferraro, N. MacCrann, Vera Gluscevic, Rachel Bean, Mathew S. Madhavacheril, Suzanne T. Staggs, Neelima Sehgal, Alexander van Engelen, Erminia Calabrese, Cristobál Sifón, William R. Coulton, Yilun Guan, Mark J. Devlin, Nicholas Battaglia, Kendrick M. Smith, J. Colin Hill, Edward J. Wollack, Alex Laguë, Bernardita Ried Guachalla, Blake D. Sherwin, Eve M. Vavagiakis
article en
6 citations

Abstract

Abstract The kinematic Sunyaev-Zel'dovich (kSZ) effect induces a non-zero density-density-temperature bispectrum, which we can use to reconstruct the large-scale velocity field from a combination of cosmic microwave background (CMB) and galaxy density measurements, in a procedure known as “kSZ velocity reconstruction”. This method has been forecast to constrain large-scale modes with future galaxy and CMB surveys, improving their measurement beyond what is possible with the galaxy surveys alone. Such measurements will enable tighter constraints on large-scale signals such as primordial non-Gaussianity, deviations from homogeneity, and modified gravity. In this work, we demonstrate a statistically significant measurement of kSZ velocity reconstruction for the first time, by applying quadratic estimators to the combination of the ACT DR6 CMB+kSZ map and the DESI LRG galaxies (with photometric redshifts) in order to reconstruct the velocity field. We do so using a formalism appropriate for the 2-dimensional projected galaxy fields that we use, which naturally incorporates the curved-sky effects important on the largest scales. We find evidence for the signal by cross-correlating with an external estimate of the velocity field from the spectroscopic BOSS survey and rejecting the null (no-kSZ) hypothesis at 3.8σ. Our work presents a first step towards the use of this observable for cosmological analyses.

Journal of Cosmology and Astroparticle PhysicsVol. 2025(05)
University of Southern California (US), Pontificia Universidad Católica de Valparaíso (CL), Goddard Space Flight Center (US), Lawrence Berkeley National Laboratory (US), University of Pittsburgh (US), Duke University (US), Wilberforce University (US), Shanghai Jiao Tong University (CN), Perimeter Institute (CA), University of Toronto (CA), York University (CA), Princeton University (US), Cornell University (US), University of Cambridge (GB), Shanghai Astronomical Observatory (CN), SLAC National Accelerator Laboratory (US), Kavli Institute for Particle Astrophysics and Cosmology (US), Canadian Institute for Theoretical Astrophysics (CA), Centre for Theoretical Physics and Astrophysics (UZ), Flatiron Health (United States) (US), Arizona State University (US), Stony Brook University (US), Columbia University (US), Cardiff University (GB), University of Pennsylvania (US), University of KwaZulu-Natal (ZA), University of California, Berkeley (US), Stanford University (US), University of Wales (GB)
National Science Foundation, National Aeronautics and Space Administration, Princeton University, University of Pennsylvania, Innovation, Science and Economic Development Canada, Compute Canada, Government of Ontario, National Energy Research Scientific Computing Center, Flatiron Health, Government of Canada, European Commission, National Research Foundation, University of Toronto, Agencia Nacional de Investigación y Desarrollo, Institut Périmètre de physique théorique, Ministry of Colleges and Universities, National Institute of Standards and Technology
Openalex Percentile: Top 3%
Cosmology and Gravitation Theories
6.93
DOIOpen Access PDFOpenAlex
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