The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters
Authors: Madhavacheril Mathew S. , Qu Frank J. , Sherwin Blake D. , MacCrann Niall , Li Yaqiong , Abril-Cabezas Irene , Ade Peter A. R. , Aiola Simone , Alford Tommy , Amiri Mandana , Amodeo Stefania , An Rui , Atkins Zachary , Austermann Jason E. , Battaglia Nicholas , Battistelli Elia Stefano , Beall James A. , Bean Rachel , Beringue Benjamin , Bhandarkar Tanay , Biermann Emily , Bolliet Boris , Bond J Richard , Cai Hongbo , Calabrese Erminia , Calafut Victoria , Capalbo Valentina , Carrero Felipe , Challinor Anthony , Chesmore Grace E. , Cho Hsiao-mei , Choi Steve K. , Clark Susan E. , Córdova Rosado Rodrigo , Cothard Nicholas F. , Coughlin Kevin , Coulton William , Crowley Kevin T. , Dalal Roohi , Darwish Omar , Devlin Mark J. , Dicker Simon , Doze Peter , Duell Cody J. , Duff Shannon M. , Duivenvoorden Adriaan J. , Dunkley Jo , Dünner Rolando , Fanfani Valentina , Fankhanel Max , Farren Gerrit , Ferraro Simone , Freundt Rodrigo , Fuzia Brittany , Gallardo Patricio A. , Garrido Xavier , Givans Jahmour , Gluscevic Vera , Golec Joseph E. , Guan Yilun , Hall Kirsten R. , Halpern Mark , Han Dongwon , Harrison Ian , Hasselfield Matthew , Healy Erin , Henderson Shawn , Hensley Brandon , Hervías-Caimapo Carlos , Hill J. Colin , Hilton Gene C. , Hilton Matt , Hincks Adam D. , Hložek Renée , Ho Shuay-Pwu Patty , Huber Zachary B. , Hubmayr Johannes , Huffenberger Kevin M. , Hughes John P. , Irwin Kent , Isopi Giovanni , Jense Hidde T. , Keller Ben , Kim Joshua , Knowles Kenda , Koopman Brian J. , Kosowsky Arthur , Kramer Darby , Kusiak Aleksandra , La Posta Adrien , Lague Alex , Lakey Victoria , Lee Eunseong , Li Zack , Limon Michele , Lokken Martine , Louis Thibaut , Lungu Marius , MacInnis Amanda , Maldonado Diego , Maldonado Felipe , Mallaby-Kay Maya , Marques Gabriela A. , McMahon Jeff , Mehta Yogesh , Menanteau Felipe , Moodley Kavilan , Morris Thomas W. , Mroczkowski Tony , Naess Sigurd , Namikawa Toshiya , Nati Federico , Newburgh Laura , Nicola Andrina , Niemack Michael D. , Nolta Michael R. , Orlowski-Scherer John , Page Lyman A. , Pandey Shivam , Partridge Bruce , Prince Heather , Puddu Roberto , Radiconi Federico , Robertson Naomi , Rojas Felipe , Sakuma Tai , Salatino Maria , Schaan Emmanuel , Schmitt Benjamin L. , Sehgal Neelima , Shaikh Shabbir , Sierra Carlos , Sievers Jon , Sifón Cristóbal , Simon Sara , Sonka Rita , Spergel David N. , Staggs Suzanne T. , Storer Emilie , Switzer Eric R. , Tampier Niklas , Thornton Robert , Trac Hy , Treu Jesse , Tucker Carole , Ullom Joel , Vale Leila R. , Van Engelen Alexander , Van Lanen Jeff , van Marrewijk Joshiwa , Vargas Cristian , Vavagiakis Eve M. , Wagoner Kasey , Wang Yuhan , Wenzl Lukas , Wollack Edward J. , Xu Zhilei , Zago Fernando , Zheng Kaiwen 
Published: February 2024

Abstract
We present cosmological constraints from a gravitational lensing mass map covering 9400 deg2 reconstructed from measurements of the cosmic microwave background (CMB) made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with measurements of baryon acoustic oscillations and big bang nucleosynthesis, we obtain the clustering amplitude σ
8 = 0.819 ± 0.015 at 1.8% precision,

S

8

≡

σ

8

(

Ω

m

/

0.3
)

0.5

=
0.840
±
0.028

, and the Hubble constant H
0 = (68.3 ± 1.1) km s−1 Mpc−1 at 1.6% precision. A joint constraint with Planck CMB lensing yields σ
8 = 0.812 ± 0.013,

S

8

≡

σ

8

(

Ω

m

/

0.3
)

0.5

=
0.831
±
0.023

, and H
0 = (68.1 ± 1.0) km s−1 Mpc−1. These measurements agree with ΛCDM extrapolations from the CMB anisotropies measured by Planck. We revisit constraints from the KiDS, DES, and HSC galaxy surveys with a uniform set of assumptions and find that S
8 from all three are lower than that from ACT+Planck lensing by levels ranging from 1.7σ to 2.1σ. This motivates further measurements and comparison, not just between the CMB anisotropies and galaxy lensing but also between CMB lensing probing z ∼ 0.5–5 on mostly linear scales and galaxy lensing at z ∼ 0.5 on smaller scales. We combine with CMB anisotropies to constrain extensions of ΛCDM, limiting neutrino masses to ∑m

ν
< 0.13 eV (95% c.l.), for example. We describe the mass map and related data products that will enable a wide array of cross-correlation science. Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the ΛCDM model, while paving a promising path for neutrino physics with lensing from upcoming ground-based CMB surveys.