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Gatti, M. [University of Chicago]

Publications and source records attributed to Gatti, M. [University of Chicago].

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Dark Energy Survey Year 6 results: Clustering redshifts and importance sampling of self-organized-maps 𝑛⁑(𝑧) realizations for 3 Γ— 2 ⁒pt samples

This work is part of a series establishing the redshift framework for the 3 Γ— 2 ⁒pt analysis of the Dark Energy Survey Year 6 (DES Y6). For DES Y6, photometric redshift distributions are estimated using self-organizing maps (SOMs), calibrated with spectroscopic and many-band photometric data. To overcome limitations from color-redshift degeneracies and incomplete spectroscopic coverage, we enhance this approach by incorporating clustering-based redshift constraints (clustering-z, or WZ) from angular cross-correlations with BOSS and eBOSS galaxies and eBOSS quasar samples. We define a WZ likelihood and apply importance sampling to a large ensemble of SOM-derived 𝑛⁑(𝑧) realizations, selecting those consistent with the clustering measurements to produce a posterior sample for each lens and source bin. The analysis uses angular scales corresponding to 1.5–5 Mpc to optimize signal-to-noise ratio while mitigating modeling uncertainties and marginalizes over redshift-dependent galaxy bias and other systematics informed by the N-body simulation CARDINAL . While a sparser spectroscopic reference sample limits WZ constraining power at 𝑧 >1.1, particularly for source bins, we demonstrate that combining SOM with WZ improves redshift accuracy and enhances the overall cosmological constraining power of DES Y6. As a result, we estimate an improvement in 𝑆 8 of approximately 10% for cosmic shear and 3 Γ—2⁒pt analysis, primarily due to the WZ calibration of the source samples.

Cosmological parameters↗
DOE OSTI2026

Dark Energy Survey: DESI-independent angular BAO measurement

In this work, we present a measurement of the angular baryon acoustic oscillation (BAO) scale from the completed Dark Energy Survey (DES) dataset excluding the area of overlap with the Dark Energy Spectroscopic Instrument (DESI). We follow the same methodology and validation process as in the DES Y6 BAO analysis. We interpret the impact of this measurement in the context of the statistical preference for 𝑀 0 ⁒𝑀 π‘Ž cold dark matter (CDM) over Λ⁒CDM when combined with DES Y5 Type Ia supernovae (SN), Planck CMB, and DESI BAO. Based on our previous work, using the full Y6 DES BAO sample, in combination with SN, CMB and DESI data release 1 (DR1) BAO, added 0.3⁒𝜎 in this preference (from 3.7⁒𝜎 to 4.0⁒𝜎), but this ignored possible correlations between datasets. Using our new DESI-independent DES BAO likelihood instead, we find a smaller increase in the statistical preference for 𝑀 0 ⁒𝑀 π‘Ž ⁒CDM, from 3.7⁒𝜎 to 3.8⁒𝜎 when using DESI DR1 BAO, and from 4.0⁒𝜎 to 4.1⁒𝜎 when updating to the more recent DESI data release 2 (DR2) BAO. These significances reduce to 3.1⁒𝜎 when using the new calibrated DES SN-Dovekie. Alongside this work, we publicly release baofit_wtheta, the BAO fitting code for the angular correlation function used in the DES Y6 BAO analysis.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Cosmology with second- and third-order shear statistics for the Dark Energy Survey: Methods and simulated analysis

We present a new pipeline designed for the robust inference of cosmological parameters using both second- and third-order shear statistics. We build a theoretical model for rapid evaluation of three-point correlations using our fastnc code and integrate it into the cosmosis framework. We measure the two-point functions πœ‰ Β± and the full configuration-dependent three-point shear correlation functions across all auto- and cross-redshift bins. We compress the three-point functions into the mass aperture statistic βŸ¨β„³$^{3}_{ap}$⟩ for a set of 796 simulated shear maps designed to model the Dark Energy Survey Year 3 data. We estimate from it the full covariance matrix and model the effects of intrinsic alignments, shear calibration biases and photometric redshift uncertainties. We apply scale cuts to minimize the contamination from the baryonic signal as modeled through hydrodynamical simulations. We find a significant improvement of 83% on the figure of merit in the Ξ© m βˆ’ 𝑆 8 plane when we add the βŸ¨β„³$^{3}_{ap}$⟩ data to πœ‰ Β± . Here, we present our findings for all relevant cosmological and systematic uncertainty parameters and discuss the complementarity of third-order and second-order statistics.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Dark Energy Survey Year 3 Results: Cosmological constraints from second- and third-order shear statistics

Here, we present a cosmological analysis of the third-order aperture mass statistic using Dark Energy Survey Year 3 (DES Y3) data. We perform a complete tomographic measurement of the three-point correlation function of the Y3 weak lensing shape catalog with the four fiducial source redshift bins. Building upon our companion methodology paper, we apply a pipeline that combines the two-point function ΞΎ Β± with the mass aperture skewness statistic ⟨ M ap 3 ⟩ , which is an efficient compression of the full shear three-point function. We use a suite of simulated shear maps to obtain a joint covariance matrix. By jointly analyzing ΞΎ Β± and ⟨ M ap 3 ⟩ measured from DES Y3 data with a Ξ› CDM model, we find S 8 = 0.780 Β± 0.015 and Ξ© m = 0.26 6 - 0.040 + 0.039 , yielding 111% of figure-of-merit improvement in the Ξ© m - S 8 plane relative to ΞΎ Β± alone, consistent with expectations from simulated likelihood analyses. With a w CDM model, we find S 8 = 0.74 9 - 0.026 + 0.027 and w 0 = - 1.39 Β± 0.31 , which gives an improvement of 22% on the joint S 8 - w 0 constraint. Our results are consistent with w 0 = - 1 . Our new constraints are compared to CMB data from the Planck satellite, and we find that with the inclusion of ⟨ M ap 3 ⟩ the existing tension between the datasets is at the level of 2.3 Οƒ . We show that the third-order statistic enables us to self-calibrate the mean photometric redshift uncertainty parameter of the highest redshift bin with little degradation in the figure of merit. Our results demonstrate the constraining power of higher-order lensing statistics and establish ⟨ M ap 3 ⟩ as a practical observable for joint analyses in current and future surveys.

Gomes, R. C. H. [University of Pennsylvania] (ORCI↗
DOE OSTI2025

Dark energy survey year 3 results: Cosmological constraints from cluster abundances, weak lensing, and galaxy clustering

Galaxy clusters provide a unique probe of the late-time cosmic structure and serve as a powerful independent test of the Λ⁒CDM model. This work presents the first set of cosmological constraints derived with ∼16,000 optically selected redMaPPer clusters across nearly 5000 deg 2 using DES year 3 datasets. Our analysis leverages a consistent modeling framework for galaxy cluster cosmology and DES-Y3 joint analyses of galaxy clustering and weak lensing (3 Γ— 2⁒pt), ensuring direct comparability with the DES-Y3 3 Γ— 2⁒pt analysis. Here, we obtain constraints of 𝑆 8 = 0.864 Β± 0.035 and Ξ© m = $0.26⁒5^{+0.019}_{βˆ’0.031}$ from the cluster-based data vector. We find that cluster constraints and 3 Γ— 2⁒pt constraints are consistent under the Λ⁒CDM model with a posterior predictive distribution (PPD) value of 0.53. The consistency between clusters and 3 Γ— 2⁒pt provides a stringent test of Λ⁒CDM across different mass and spatial scales. Jointly analyzing clusters with 3 Γ— 2⁒pt further improves cosmological constraints, yielding 𝑆 8 = $0.81⁒1^{+0.022}_{βˆ’0.020}$ and Ξ© m = $0.29⁒4^{+0.022}_{βˆ’0.033}$, a 24% improvement in the Ξ© m βˆ’ 𝑆 8 figure of merit over 3 Γ— 2⁒pt alone. Moreover, we find no significant deviation from the Planck CMB constraints with a probability to exceed (PTE) value of 0.6, significantly reducing previous 𝑆 8 tension claims. Finally, combining DES 3 Γ— 2⁒pt, DES clusters, and Planck CMB places an upper limit on the sum of neutrino masses of βˆ‘π‘š 𝜈 < 0.26 eV at 95% confidence under the Λ⁒CDM model. These results establish optically selected clusters as a key cosmological probe and pave the way for cluster-based analyses in upcoming stage-IV surveys such as LSST, Euclid, and Roman.

Abbott, T. M. C. [NSF’s National Optical-Infrared β†—