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1. The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters

   https://doi.org/10.3847/1538-4357/acff5f  

   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; et al (February 2024, The Astrophysical Journal)

   Abstract We present cosmological constraints from a gravitational lensing mass map covering 9400 deg²reconstructed 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 amplitudeσ₈= 0.819 ± 0.015 at 1.8% precision, $S_8\equiv {\sigma }_8{\left({\mathrm{\Omega }}_{\mathrm{m}}/0.3\right)}^{0.5}=0.840\pm 0.028$ , and the Hubble constantH₀= (68.3 ± 1.1) km s⁻¹Mpc⁻¹at 1.6% precision. A joint constraint with Planck CMB lensing yieldsσ₈= 0.812 ± 0.013, $S_8\equiv {\sigma }_8{\left({\mathrm{\Omega }}_{\mathrm{m}}/0.3\right)}^{0.5}=0.831\pm 0.023$ , andH₀= (68.1 ± 1.0) km s⁻¹Mpc⁻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 thatS₈from all three are lower than that from ACT+Planck lensing by levels ranging from 1.7σto 2.1σ. This motivates further measurements and comparison, not just between the CMB anisotropies and galaxy lensing but also between CMB lensing probingz∼ 0.5–5 on mostly linear scales and galaxy lensing atz∼ 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. 

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2. The Atacama Cosmology Telescope: DR6 power spectra, likelihoods and ΛCDM parameters

   https://doi.org/10.1088/1475-7516/2025/11/062  

   Louis, Thibaut; La_Posta, Adrien; Atkins, Zachary; Jense, Hidde T; Abril-Cabezas, Irene; Addison, Graeme E; Ade, Peter AR; Aiola, Simone; Alford, Tommy; Alonso, David; et al (November 2025, Journal of Cosmology and Astroparticle Physics)

   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 deg²of sky in bands centered at 98, 150 and 220 GHz, with white noise levels three times lower thanPlanckin polarization. We find that the ACT angular power spectra estimated over 10,000 deg², 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-scalePlanckdata, 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 thePlanckpower spectra or from ACT combined withWMAPdata, as well as from either temperature or polarization in the joint P-ACT dataset. When combined with CMB lensing from ACT andPlanck, and baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI DR1), we measure a baryon density of Ω_bh²= 0.0226 ± 0.0001, a cold dark matter density of Ω_ch²= 0.118 ± 0.001, a Hubble constant ofH₀= 68.22 ± 0.36 km/s/Mpc, a spectral index ofn_s= 0.974 ± 0.003, and an amplitude of density fluctuations ofσ₈= 0.813 ± 0.005. Including the DESI DR2 data tightens the Hubble constant toH₀= 68.43 ± 0.27 km/s/Mpc; ΛCDM parameters agree between the P-ACT and DESI DR2 data at the 1.6σlevel. 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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3. DESI 2024 VI: cosmological constraints from the measurements of baryon acoustic oscillations

   https://doi.org/10.1088/1475-7516/2025/02/021  

   Adame, AG; Aguilar, J; Ahlen, S; Alam, S; Alexander, DM; Alvarez, M; Alves, O; Anand, A; Andrade, U; Armengaud, E; et al (February 2025, Journal of Cosmology and Astroparticle Physics)

   Abstract We present cosmological results from the measurement of baryon acoustic oscillations (BAO) in galaxy, quasar and Lyman-αforest tracers from the first year of observations from the Dark Energy Spectroscopic Instrument (DESI), to be released in the DESI Data Release 1. DESI BAO provide robust measurements of the transverse comoving distance and Hubble rate, or their combination, relative to the sound horizon, in seven redshift bins from over 6 million extragalactic objects in the redshift range 0.1 <z< 4.2. To mitigate confirmation bias, a blind analysis was implemented to measure the BAO scales. DESI BAO data alone are consistent with the standard flat ΛCDM cosmological model with a matter density Ω_m=0.295±0.015. Paired with a baryon density prior from Big Bang Nucleosynthesis and the robustly measured acoustic angular scale from the cosmic microwave background (CMB), DESI requiresH₀=(68.52±0.62) km s^-1Mpc^-1. In conjunction with CMB anisotropies fromPlanckand CMB lensing data fromPlanckand ACT, we find Ω_m=0.307± 0.005 andH₀=(67.97±0.38) km s^-1Mpc^-1. Extending the baseline model with a constant dark energy equation of state parameterw, DESI BAO alone requirew=-0.99^+0.15_-0.13. In models with a time-varying dark energy equation of state parametrised byw₀andw_a, combinations of DESI with CMB or with type Ia supernovae (SN Ia) individually preferw₀> -1 andw_a< 0. This preference is 2.6σfor the DESI+CMB combination, and persists or grows when SN Ia are added in, giving results discrepant with the ΛCDM model at the 2.5σ, 3.5σor 3.9σlevels for the addition of the Pantheon+, Union3, or DES-SN5YR supernova datasets respectively. For the flat ΛCDM model with the sum of neutrino mass ∑m_νfree, combining the DESI and CMB data yields an upper limit ∑m_ν< 0.072 (0.113) eV at 95% confidence for a ∑m_ν> 0 (∑m_ν> 0.059) eV prior. These neutrino-mass constraints are substantially relaxed if the background dynamics are allowed to deviate from flat ΛCDM. 

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4. The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and Its Implications for Structure Growth

   https://doi.org/10.3847/1538-4357/acfe06  

   Qu, Frank J; Sherwin, Blake D; Madhavacheril, Mathew S; Han, Dongwon; Crowley, Kevin T; Abril-Cabezas, Irene; Ade, Peter_A R; Aiola, Simone; Alford, Tommy; Amiri, Mandana; et al (February 2024, The Astrophysical Journal)

   Abstract We present new measurements of cosmic microwave background (CMB) lensing over 9400 deg²of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB data set, which consists of five seasons of ACT CMB temperature and polarization observations. We determine the amplitude of the CMB lensing power spectrum at 2.3% precision (43σsignificance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. To ensure that our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. Our CMB lensing power spectrum measurement provides constraints on the amplitude of cosmic structure that do not depend on Planck or galaxy survey data, thus giving independent information about large-scale structure growth and potential tensions in structure measurements. The baseline spectrum is well fit by a lensing amplitude ofA_lens= 1.013 ± 0.023 relative to the Planck 2018 CMB power spectra best-fit ΛCDM model andA_lens= 1.005 ± 0.023 relative to the ACT DR4 + WMAP best-fit model. From our lensing power spectrum measurement, we derive constraints on the parameter combination $S_8^{\mathrm{CMBL}}\equiv {\sigma }_8{\left({\mathrm{\Omega }}_m/0.3\right)}^{0.25}$ of $S_8^{\mathrm{CMBL}}=0.818\pm 0.022$ from ACT DR6 CMB lensing alone and $S_8^{\mathrm{CMBL}}=0.813\pm 0.018$ when combining ACT DR6 and PlanckNPIPECMB lensing power spectra. These results are in excellent agreement with ΛCDM model constraints from Planck or ACT DR4 + WMAP CMB power spectrum measurements. Our lensing measurements from redshiftsz∼ 0.5–5 are thus fully consistent with ΛCDM structure growth predictions based on CMB anisotropies probing primarilyz∼ 1100. We find no evidence for a suppression of the amplitude of cosmic structure at low redshifts. 

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5. Modified gravity constraints from the full shape modeling of clustering measurements from DESI 2024

   https://doi.org/10.1088/1475-7516/2025/09/053  

   Ishak, M; Pan, J; Calderon, R; Lodha, K; Valogiannis, G; Aviles, A; Niz, G; Yi, L; Zheng, C; Garcia-Quintero, C; et al (September 2025, Journal of Cosmology and Astroparticle Physics)

   Abstract We present cosmological constraints on deviations from general relativity (GR) from the first-year of clustering observations from the Dark Energy Spectroscopic Instrument (DESI) in combination with other available datasets including the CMB data from Planck with CMB-lensing from Planck and ACT, BBN constraints on the physical baryon density, the galaxy weak lensing and clustering from DESY3 and supernova data from DESY5. We first consider the  μ(a,k)–Σ(a,k) modified gravity (MG) parameterization (as well asη(a,k)) in a ΛCDM and aw₀w_aCDM cosmological backgrounds. Using a functional form for time-only evolution givesμ₀= 0.11^+0.44_-0.54from DESI(FS+BAO)+BBN and a wide prior onn_s. Using DESI(FS+BAO)+CMB+DESY3+DESY5-SN, we obtainμ₀= 0.05 ± 0.22 and Σ₀= 0.008 ± 0.045 and similarlyμ₀= 0.02^+0.19_-0.24andη₀= 0.09^+0.36_-0.60, in an ΛCDM background. Inw₀w_aCDM we obtainμ₀= -0.24^+0.32_-0.28and Σ₀= 0.006 ± 0.043, consistent with GR, and we still find a preference of the data for a dynamical dark energy withw₀> -1 andw_a< 0. Using functional dependencies in both time and scale givesμ₀and Σ₀with a same level of precision as above but other scale MG parameters remain hard to constrain. We then move to binned parameterizations in a ΛCDM background starting with two bins in redshift and obtain,μ₁= 1.02 ± 0.13,μ₂= 1.04 ± 0.11, Σ₁= 1.021 ± 0.029 and Σ₂= 1.022^+0.027_-0.023, all consistent with the unity value of GR in the binning formalism. We then extend the analysis to combine two bins in redshift and two in scale giving 8 MG parameters that we find all consistent with GR. We note that we find here that the tension reported in previous studies about Σ₀being inconsistent with GR when using Planck PR3 data goes away when we use the recentLoLLiPoP+HiLLiPoPlikelihoods. As noted in previous studies, this seems to indicate that the tension is indeed related to the CMB lensing anomaly in PR3 which is also resolved when using the recent likelihoods. We then constrain the class of Horndeski theory in the effective field theory of dark energy approach. We consider both EFT-basis andα-basis in the analysis. Assuming a power law parameterization for the EFT function Ω, which controls non-minimal coupling, we obtain Ω₀= 0.012^+0.001_-0.012ands₀= 0.996^+0.54_-0.20from the combination of DESI(FS+BAO)+DESY5SN+CMB in a ΛCDM background, which are consistent with GR. Similar results are obtained when using theα-basis and assuming no-braiding (α_B= 0) giving  c_M< 1.14 at 95% CL in a ΛCDM background, also in agreement with GR. However, we see a mild yet consistent indication forc_B> 0 whenα_Bis allowed to vary which will require further study to determine whether this is due to systematics or new physics. 

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