Qu, Frank J., Hang, Qianjun, Farren, Gerrit, Bolliet, Boris, Aguilar, Jessica Nicole, Ahlen, Steven, Alam, Shadab, Brooks, David, Cai, Yan-Chuan, Calabrese, Erminia ![]() ![]() |
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Abstract
We measure the growth of cosmic density fluctuations on large scales and across the redshift range 0.3<0.8 through galaxy clustering and the cross-correlation of the ACT data release 6 cosmic microwave background (CMB) lensing map and galaxies from the Dark Energy Spectroscopic Instrument Legacy Survey, using three galaxy samples spanning the redshifts of 0.3≲z≲0.45, 0.45≲z≲0.6, 0.6≲z≲0.8. We adopt a scale cut where nonlinear effects are negligible, so that the cosmological constraints are derived from the linear regime. We determine the amplitude of matter fluctuations over all three redshift bins using Atacama Cosmology Telescope (ACT) data alone to be S8≡σ8(Ωm/0.3)0.5=0.772±0.040 in a joint analysis combining the three redshift bins and ACT lensing alone. Using a combination of ACT and data we obtain S8=0.765±0.032. The lowest redshift bin used is the least constraining and exhibits a ∼2σ tension with the other redshift bins; thus we also report constraints excluding the first redshift bin, giving S8=0.785±0.033 for the combination of ACT and . This result is in excellent agreement at the 0.3σ level with measurements from galaxy lensing, but is 1.8σ lower than predictions based on primary CMB data. Understanding whether this hint of discrepancy in the growth of structure at low redshifts arises from a fluctuation, from systematics in data, or from new physics is a high priority for forthcoming CMB lensing and galaxy cross-correlation analyses. Published by the American Physical Society 2025
Item Type: | Article |
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Date Type: | Published Online |
Status: | Published |
Schools: | Schools > Physics and Astronomy |
Additional Information: | License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2025-05-02 |
Publisher: | American Physical Society |
ISSN: | 2470-0010 |
Date of First Compliant Deposit: | 2 June 2025 |
Date of Acceptance: | 10 April 2025 |
Last Modified: | 02 Jun 2025 11:15 |
URI: | https://orca.cardiff.ac.uk/id/eprint/178645 |
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