A nonstandard Halo Mass Function as a solution to the structuregrowth tension, application to KiDS1000 and DESy3
Abstract
Semianalytical computation of the matter power spectrum often relies on the halo mass function (HMF) as a key component. In this paper, we explore how certain variations of the HMF affect the modelling of the matter power spectra and quantify the impact on the structure growth parameter $S_8 = \sigma_8\sqrt{\Omega_\mathrm{m}/0.3}$. We use the weak gravitational lensing 2point correlation functions from both Kilo Degree Survey (KiDS1000) and Dark Energy Survey (DESy3) to constrain the HMF parameters, which are sensitive to dark matter properties, structure formation, and baryonic feedback. When assuming the Planck cosmology, the canonical HMF parameters are rejected at more than $2\sigma$ level for both KiDS and DES, where reconstructed HMF from these posteriors give a $48.8\%^{+8.3\%}_{9.4\%}$ lower for KiDS1000 and a $29.5\%^{+8.5\%}_{8.5\%}$ lower for DESy3 in terms of total halo mass larger than $M_\mathrm{Halo} > 10^{14} M_\odot$ compared to a canonical HMF model. In addition, a Plancklike $S_8$ is also preferred if massive haloes were to have a $\sim 20\%$ lower abundance compared to a canonical halo mass function. Under one of these alternative HMFs, we found $S_8 \sim 0.826_{0.019}^{+0.021}$ for KiDS1000 and $0.851_{0.021}^{+0.020}$ for DESy3. Our work suggests that varying the halo abundance provides an alternative to varying the matter power spectrum when exploring possible solutions to the $S_8$ tension. By comparing the posteriors of both cosmological and HMF parameters between two different surveys (KiDS1000 and DESy3), we are also testing the selfconsistency of the cosmological interpretation at a level that has corresponding particle and/or astrophysical interpretations.
 Publication:

arXiv eprints
 Pub Date:
 February 2023
 DOI:
 10.48550/arXiv.2302.00780
 arXiv:
 arXiv:2302.00780
 Bibcode:
 2023arXiv230200780G
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 20 pages (including appendixes), 17 figures, 3 tables, main results in Figs. 3,4&