Weighing cosmic structures with clusters of galaxies and the intergalactic medium
Abstract
We present an analysis aimed at combining cosmological constraints from number counts of galaxy clusters identified through the SunyaevZeldovich effect, obtained with the South Pole Telescope (SPT), and from Lyman α spectra obtained with the MIKE/HIRES and Xshooter spectrographs. The SPT cluster analysis relies on mass calibration based on weak lensing measurements, while the Lyman α analysis is built over mock spectra extracted from hydrodynamical simulations. The resulting constraints exhibit a tension (~3.3σ) between the low σ_{8} values preferred by the lowredshift cluster data, $\sigma _8=0.74 ^{+0.03}_{0.04}$, and the higher one preferred by the highredshift Lyman α data, $\sigma _8=0.91 ^{+0.03}_{0.03}$. We present a detailed analysis to understand the origin of this tension and to establish whether it arises from systematic uncertainties related to the assumptions underlying the analyses of cluster counts and/or Lyman α forest. We found this tension to be robust with respect to the choice of modelling of the IGM, even when including possible systematics from unaccounted subDamped Lyman α (DLA) and Lymanlimit systems (LLS) in the Lyman α data. We conclude that to solve this tension would require a large bias on the cluster mass estimate, or large unaccounted errors on the Lyman α mean fluxes. Our results have important implications for future analyses based on cluster number counts from future large photometric surveys (e.g. Euclid and LSST) and on larger samples of highredshift quasar spectra (e.g. DESI and WEAVE surveys). If confirmed at the much higher statistical significance reachable by such surveys, this tension could represent a significant challenge for the standard ΛCDM paradigm.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 September 2022
 DOI:
 10.1093/mnras/stac1825
 arXiv:
 arXiv:2202.00974
 Bibcode:
 2022MNRAS.515..857E
 Keywords:

 methods: numerical;
 galaxies: clusters: intergalactic medium;
 largescale structure of Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Theory
 EPrint:
 14 pages, 8 figures