Dark Energy Survey Year 3 results: Cosmology with peaks using an emulator approach

Abstract

We constrain the matter density ${\Omega }_{\mathrm{m}}$ and the amplitude of density fluctuations ${\sigma }_8$ within the $\Lambda$CDM cosmological model with shear peak statistics and angular convergence power spectra using mass maps constructed from the first three years of data of the Dark Energy Survey (DES Y3). We use tomographic shear peak statistics, including cross-peaks: peak counts calculated on maps created by taking a harmonic space product of the convergence of two tomographic redshift bins. Our analysis follows a forward-modelling scheme to create a likelihood of these statistics using N-body simulations, using a Gaussian process emulator. We include the following lensing systematics: multiplicative shear bias, photometric redshift uncertainty, and galaxy intrinsic alignment. Stringent scale cuts are applied to avoid biases from unmodelled baryonic physics. We find that the additional non-Gaussian information leads to a tightening of the constraints on the structure growth parameter yielding $S_8\equiv {\sigma }_8\sqrt{{\Omega }_{\mathrm{m}}/0.3}=0.797_{-0.013}^{+0.015}$ (68% confidence limits), with a precision of 1.8%, an improvement of ~38% compared to the angular power spectra only case. The results obtained with the angular power spectra and peak counts are found to be in agreement with each other and no significant difference in $S_8$ is recorded. We find a mild tension of $1.5\sigma$ between our study and the results from Planck 2018, with our analysis yielding a lower $S_8$. Furthermore, we observe that the combination of angular power spectra and tomographic peak counts breaks the degeneracy between galaxy intrinsic alignment $A_{\mathrm{IA}}$ and $S_8$, improving cosmological constraints. We run a suite of tests concluding that our results are robust and consistent with the results from other studies using DES Y3 data.

References in corpus (18)

• The NumPy array: a structure for efficient numerical computation
• Dark energy constraints from cosmic shear power spectra: impact of intrinsic alignments on photometric redshift requirements
• Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample
• Lensing is Low: Cosmology, Galaxy Formation, or New Physics?
• CFHTLenS: Cosmological constraints from a combination of cosmic shear two-point and three-point correlations
• KiDS-450: Cosmological Constraints from Weak Lensing Peak Statistics - II: Inference from Shear Peaks using N-body Simulations
• PSF calibration requirements for dark energy from cosmic shear
• Means of confusion: how pixel noise affects shear estimates for weak gravitational lensing
• A filament of dark matter between two clusters of galaxies
• The Mira-Titan Universe II: Matter Power Spectrum Emulation
• KiDS-450: Cosmological Constraints from Weak Lensing Peak Statistics-I: Inference from Analytical Prediction of High Signal-to-Noise Ratio Convergence Peaks
• Emulating the CFHTLenS Weak Lensing data: Cosmological Constraints from moments and Minkowski functionals
• Shear Power Spectrum Reconstruction using Pseudo-Spectrum Method
• Non-Gaussian estimates of tensions in cosmological parameters
• Impact of Baryonic Processes on Weak Lensing Cosmology: Power Spectrum, Non-Local Statistics, and Parameter Bias
• Maximal compression of the redshift space galaxy power spectrum and bispectrum
• Going deep with Minkowski functionals of convergence maps
• The impact of spurious shear on cosmological parameter estimates from weak lensing observables