Tuesday, April 4, 2023

Using dark matter distribution to test the cosmological model


We present cosmology results from a blinded joint analysis of cosmic shear, ξ±(ϑ), galaxy-galaxy weak lensing, ΔΣ(R), and projected galaxy clustering, wp(R), measured from the Hyper Suprime-Cam three-year (HSC-Y3) shape catalog and the Sloan Digital Sky Survey (SDSS) DR11 spectroscopic galaxy catalog - a 3×2pt cosmology analysis.

We obtain a robust constraint on the cosmological parameters for the flat ΛCDM model: S8=σ8(Ωm/0.3)0.5=0.763+0.040−0.036 (68% C.I.), or the best-constrained parameter given by S′8=σ8(Ωm/0.3)0.22=0.721±0.028, determined with about 4% fractional precision.


An international team of astrophysicists and cosmologists at various institutes including the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) have submitted a set of five papers, measuring a value for the "clumpiness" of the universe's dark matter, known to cosmologists as S8, of 0.76, which aligns with values that other gravitational lensing surveys have found in looking at the relatively recent universe, but it does not align with the value of 0.83 derived from the cosmic microwave background, which dates back to the universe's origins when the universe was about 380,000 years old. 

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