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