KiDS1000 and DESY1 combined: Cosmology from peak count statistics
Abstract
We analyse the fourth data release of the Kilo Degree Survey (KiDS1000) and extract cosmological parameter constraints based on the cosmic shear peak count statistics. Peaks are identified in aperture mass maps in which the filter is maximally sensitive to angular scales in the range 24arcmin, probing deep into the nonlinear regime of structure formation. We interpret our results with a simulationbased inference pipeline, sampling over a broad $w$CDM prior volume and marginalising over uncertainties on shape calibration, photometric redshift distribution, intrinsic alignment and baryonic feedback. Our measurements constrain the structure growth parameter and the amplitude of the nonlinear intrinsic alignment model to $\Sigma_8 \equiv \sigma_8\left[\Omega_{\rm m}/0.3\right]^{0.60}=0.765^{+0.030}_{0.030}$ and $A_{\rm IA}= 0.71^{+0.42}_{0.42}$, respectively, in agreement with previous KiDS1000 results based on twopoint shear statistics. These results are robust against modelling of the nonlinear physics, different scale cuts and selections of tomographic bins. The posterior is also consistent with that from the Dark Energy Survey Year1 peak count analysis presented in HarnoisDéraps et al (2021), and hence we jointly analyse both surveys. We obtain $\Sigma_8^{\rm joint} \equiv \sigma_8\left[\Omega_{\rm m}/0.3\right]^{0.57}=0.759^{+0.020}_{0.017}$, in agreement with the Planck $w$CDM results. The shearCMB tension on this parameter increases to $3.1\sigma$ when forcing $w=1.0$, and to $4.1\sigma$ if comparing instead with $S_{8,\Lambda{\rm CDM}}^{\rm joint} = 0.736^{+0.016}_{0.018}$, one of the tightest constraints to date on this quantity. (abridged)
 Publication:

arXiv eprints
 Pub Date:
 May 2024
 DOI:
 10.48550/arXiv.2405.10312
 arXiv:
 arXiv:2405.10312
 Bibcode:
 2024arXiv240510312H
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 25 pages, 20 figures. comments welcome