One of the persistent tensions in cosmology measurements, that has attracted less attention from the general public than the Hubble tension, is the value of a parameter called S8 (which measures "clustering amplitude" at a cosmological level) estimated from the cosmic background radiation measurements and the measurement from other means. New data from the Dark Energy Survey (DES) weakens that tension.
Cosmology from weak gravitational lensing has been limited by astrophysical uncertainties in baryonic feedback and intrinsic alignments.
By calibrating these effects using external data, we recover non-linear information, achieving a 2% constraint on the clustering amplitude, S8, resulting in a factor of two improvement on the ΛCDM constraints relative to the fiducial Dark Energy Survey Year 3 model. The posterior, S8 = 0.832+0.013−0.017, shifts by 1.5σ to higher values, in closer agreement with the cosmic microwave background result for the standard six-parameter ΛCDM cosmology.
Our approach uses a star-forming 'blue' galaxy sample with intrinsic alignment model parameters calibrated by direct spectroscopic measurements, together with a baryonic feedback model informed by observations of X-ray gas fractions and kinematic Sunyaev-Zel'dovich effect profiles that span a wide range in halo mass and redshift. Our results provide a blueprint for next-generation surveys: leveraging galaxy properties to control intrinsic alignments and external gas probes to calibrate feedback, unlocking a substantial improvement in the precision of weak lensing surveys.
Leah Bigwood, et al., "Confronting cosmic shear astrophysical uncertainties: DES Year 3 revisited" arXiv:2512.04209 (December 3, 2025).
New astronomy observations also strongly constrains multi-field cosmological inflation models. And, another study combining data from multiple collaborations, strongly disfavors cosmological "inflation models preferred by Planck alone, such as Higgs, Starobinsky, and exponential α-attractors, in favor of other models, such as polynomial α-attractors," based upon its new measurements of cosmological parameter n(s) (the primordial power spectrum).
Finally, there were several new preprints today exploring the WIMP dark matter hypothesis, which is irritating because the WIMP dark matter hypothesis has been almost completely ruled out by a variety of independent means.
5 comments:
In the 100 year anniversary of Quantum in Science magazine this week the intro article manages to refer to String Theory in a very positive way. You would be irritated.
:(
You are correct.
Ok, more seriously, looking at figure 2 of "Homo sapiens-specific evolution unveiled by ancient southern African genomes" in Nature last week https://rdcu.be/eUzbP, they show at least two of the Final Late Stone Age samples as heavily pulled towards the French sample in PCA space. I guess it could be how different vector can add up to same point, but it sure smells of contamination.
Retract the above, when they turn lsqproj=NO (in the Supplement) then the weirdness goes away. Eurogenes had warned of this but it's the first time I've seen it so clearly.
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