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arXiv · 2511.23417

Detection of the Pairwise Kinematic Sunyaev-Zel'dovich Effect and Pairwise Velocity with DESI DR1 Galaxies and ACT DR6 and Planck CMB Data

Yulin Gong·Patricio A. Gallardo·Rachel Bean·Jenna Moore·Eve M. Vavagiakis·Nicholas Battaglia·Boryana Hadzhiyska·Yun-Hsin Hsu·Jessica Nicole Aguilar·Steven Ahlen·Davide Bianchi·David Brooks·Todd Claybaugh·Rebecca Canning·Mark Devlin·Peter Doel·Axel de la Macorra·Simone Ferraro·Andreu Font-Ribera·Jaime E. Forero-Romero·Enrique Gaztañaga·Gaston Gutierrez·Satya Gontcho A Gontcho·Julien Guy·Klaus Honscheid·Cullan Howlett·R. Henry Liu·Mustapha Ishak·Dick Joyce·Anthony Kremin·Claire Lamman·Michael Levi·Martin Landriau·Marc Manera·Aaron Meisner·Ramon Miquel·Michael D. Niemack·Seshadri Nadathur·Will Percival·Francisco Prada·Graziano Rossi·Bernardita Ried Guachalla·Eusebio Sanchez·Hee-Jong Seo·David Sprayberry·David Schlegel·Cristóbal Sifón·Michael Schubnell·Joseph Harry Silber·Gregory Tarlé·Benjamin Alan Weaver·Rongpu Zhou·Hu Zou
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Abstract

We present a 9.3-sigma detection of the pairwise kinematic Sunyaev-Zeldovich (kSZ) effect by combining a sample of 913,286 Luminous Red Galaxies (LRGs) from the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1) catalog and co-added Atacama Cosmology Telescope (ACT DR6) and Planck cosmic microwave background (CMB) temperature maps. This represents the highest-significance pairwise kSZ measurement to date. The analysis uses three ACT CMB temperature maps: co-added 150 GHz, total frequency maps, and a component-separated Internal Linear Combination (ILC) map, all of which cover 19,000 square degrees of the sky from Advanced ACTPol observations conducted between 2017 and 2022. Comparison of the results of these three maps serves as a consistency check for potential foreground contamination that may depend on the observation frequency. An estimate of the best-fit mass-averaged optical depth is obtained by comparing the pairwise kSZ curve with the linear-theory prediction of the pairwise velocity under the best-fit Planck cosmology, and is compared with predictions from simulations. This estimate serves as a reference point for future comparisons with thermal SZ-derived optical depth measurements for the same DESI cluster samples, which will be presented in a companion paper. Finally, we employ a machine-learning approach trained on simulations to estimate the optical depth for 456,803 DESI LRG-identified clusters within the simulated mass range (greater than about 1e13 solar masses). These are combined with the measured kSZ signal to infer the individual cluster peculiar velocities, providing the opportunity to constrain the behavior of gravity and the dark sector over a range of cosmic scales and epochs.

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Yulin Gong, Patricio A. Gallardo, Rachel Bean, Jenna Moore, Eve M. Vavagiakis, Nicholas Battaglia, Boryana Hadzhiyska, Yun-Hsin Hsu, Jessica Nicole Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Todd Claybaugh, Rebecca Canning, Mark Devlin, Peter Doel, Axel de la Macorra, Simone Ferraro, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztañaga, Gaston Gutierrez, Satya Gontcho A Gontcho, Julien Guy, Klaus Honscheid, Cullan Howlett, R. Henry Liu, Mustapha Ishak, Dick Joyce, Anthony Kremin, Claire Lamman, Michael Levi, Martin Landriau, Marc Manera, Aaron Meisner, Ramon Miquel, Michael D. Niemack, Seshadri Nadathur, Will Percival, Francisco Prada, Graziano Rossi, Bernardita Ried Guachalla, Eusebio Sanchez, Hee-Jong Seo, David Sprayberry, David Schlegel, Cristóbal Sifón, Michael Schubnell, Joseph Harry Silber, Gregory Tarlé, Benjamin Alan Weaver, Rongpu Zhou, Hu Zou. 2026-03-20. Detection of the Pairwise Kinematic Sunyaev-Zel'dovich Effect and Pairwise Velocity with DESI DR1 Galaxies and ACT DR6 and Planck CMB Data. https://arxiv.org/abs/2511.23417

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