If the growth suppression associated with S8 is physical, can the data determine when it began?
Public summary of an internal test, not yet independently validated or published.
Question investigated
If the growth suppression associated with S8 is physical, can the data determine when it began?
Test conditions
Fit late-time suppression with two parameters over prespecified ranges. Combine summaries of cosmic microwave background lensing, DESI growth and weak lensing; compare with the standard model including neutrinos and repeat the analysis with one probe excluded at a time.
Result
The summaries analyzed point to reduced growth at low redshift, but do not reliably locate the onset of a physical suppression. The result does not determine whether the difference originated at late times or was already present at high redshift.
Physical interpretation
The analysis tests a phenomenological description of late-time growth suppression. Even a preference for that description would not identify a specific particle or interaction.