Astronomy and Astrophysical Research
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Abstract
Abstract
Abstract We present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, measured from the Data Release 6 maps made from Atacama Cosmology Telescope (ACT) data. These cover 19,000 deg 2 of sky in bands centered at 98, 150 and 220 GHz, with white noise levels three times lower than Planck in polarization. We find that the ACT angular power spectra estimated over 10,000 deg 2 , and measured to arcminute scales in TT, TE and EE, are well fit by the sum of CMB and foregrounds, where the CMB spectra are described by the ΛCDM model. Combining ACT with larger-scale Planck data, the joint P-ACT dataset provides tight limits on the ingredients, expansion rate, and initial conditions of the universe. We find similar constraining power, and consistent results, from either the Planck power spectra or from ACT combined with WMAP data, as well as from either temperature or polarization in the joint P-ACT dataset. When combined with CMB lensing from ACT and Planck , and baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI DR1), we measure a baryon density of Ω b h 2 = 0.0226 ± 0.0001, a cold dark matter density of Ω c h 2 = 0.118 ± 0.001, a Hubble constant of H 0 = 68.22 ± 0.36 km/s/Mpc, a spectral index of n s = 0.974 ± 0.003, and an amplitude of density fluctuations of σ 8 = 0.813 ± 0.005. Including the DESI DR2 data tightens the Hubble constant to H 0 = 68.43 ± 0.27 km/s/Mpc; ΛCDM parameters agree between the P-ACT and DESI DR2 data at the 1.6 σ level. We find no evidence for excess lensing in the power spectrum, and no departure from spatial flatness. The contribution from Sunyaev-Zel'dovich (SZ) anisotropy is detected at high significance; we find evidence for a tilt with suppressed small-scale power compared to our baseline SZ template spectrum, consistent with hydrodynamical simulations with feedback.
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@article{Louis2025Atacama,
title = {The Atacama Cosmology Telescope: DR6 power spectra, likelihoods and ΛCDM parameters},
author = {Thibaut Louis and Adrien La Posta and Zachary Atkins and Hidde T. Jense and I. Abril-Cabezas and Graeme E. Addison and P. A. R. Ade and Simone Aiola and Tommy Alford and David Alonso and M. Amiri and Rui An and Jason E. Austermann and Eleonora Barbavara and Nicholas Battaglia and E. S. Battistelli and James A. Beall and Rachel Bean and Ali Beheshti and Benjamin Beringue and Tanay Bhandarkar and Emily Biermann and Boris Bolliet and J. Richard Bond and Erminia Calabrese and Valentina Capalbo and Felipe Carrero and Grace Chesmore and Hsiao-Mei Cho and Steve K. Choi and Susan E. Clark and Nicholas F. Cothard and Kevin Coughlin and William Coulton and Devin Crichton and Kevin T. Crowley and Simon Dicker and Cody J. Duell and Shannon Duff and Adriaan J. Duivenvoorden and Jo Dunkley and Rolando Dünner and Carmen Embil Villagra and Max Fankhanel and Gerrit S. Farren and Simone Ferraro and A. Foster and Rodrigo Freundt and Brittany Fuzia and Patricio A. Gallardo and X. Garrido and M. Gerbino and S. Giardiello and Ajay Gill and Jahmour J. Givans and Joseph E. Golec and Yulin Gong and Yilun Guan and M. Halpern and Matthew Hasselfield and Erin Healy and Shawn Henderson and Brandon S. Hensley and Carlos Hervías-Caimapo and J. Colin Hill and G. C. Hilton and Matt Hilton and Adam D. Hincks and Renée Hložek and Shuay-Pwu Patty Ho and J. C. Hood and Erika Hornecker and Zachary B. Huber and Johannes Hubmayr and K. M. Huffenberger and John P. Hughes and Margaret Ikape and K. D. Irwin and Giovanni Isopi and Joshua Kim and Kenda Knowles and Brian J. Koopman and Arthur Kosowsky and Darby Kramer and Aleksandra Kusiak and Alex Laguë and Victoria Lakey and Eunseong Lee and Yaqiong Li and Zack Li and M. Limon and Martine Lokken},
journal = {Journal of Cosmology and Astroparticle Physics},
year = {2025},
doi = {10.1088/1475-7516/2025/11/062},
url = {https://doi.org/10.1088/1475-7516/2025/11/062}
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