# It's not $σ_8$ : constraining the non-linear matter power spectrum with the Dark Energy Survey Year-5 supernova sample

**Authors:** Paul Shah, T. M. Davis, M. Vincenzi, P. Armstrong, D. Brout, R. Camilleri, L. Galbany, M. S. S. Gill, D. Huterer, N. Jeffrey, O. Lahav, J. Lee, C. Lidman, A. Möller, M. Sullivan, L. Whiteway, P. Wiseman, S. Allam, M. Aguena, J. Annis  
**arXiv:** [2501.19117](https://arxiv.org/abs/2501.19117)  
**Date:** 2025-01-31  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2501.19117v1/

## Key points

- Researchers explore weak gravitational lensing magnification of Type Ia supernovae (SNe Ia) and its sensitivity to matter power spectrum on scales $k>1 h$ Mpc$^{-1}.
- Caution against solely interpreting SNe Ia lensing in terms of linear power, emphasize need to consider non-linear effects.
- Compute probability density function of SNe Ia magnification with respect to standard cosmological parameters and empirical parameter $A_{\rm mod}$.
- Determine $A_{\rm mod} = 0.77^{+0.69}_{-0.40}$ within a 68% credible interval around the median, indicating potential power suppression with $A_{\rm mod} < 1.09$ at 68% credibility.
- Investigation sheds light on complex interplay between cosmological parameters and modifications to matter power spectrum at non-linear scales, providing insights for refining understanding of dark energy and cosmic acceleration.
- Importance of considering broader range of physical mechanisms beyond traditional models in elucidating complexities of universe's evolution.

## Summary

The researchers in this study explore the weak gravitational lensing magnification of Type Ia supernovae (SNe Ia) and its sensitivity to the matter power spectrum on scales $k>1 h$ Mpc$^{-1}$. They caution against solely interpreting SNe Ia lensing in terms of linear power and emphasize the need to consider non-linear effects. By computing the probability density function of SNe Ia magnification with respect to standard cosmological parameters and an empirical parameter $A_{\rm mod}$, which characterizes modifications to the matter power on non-linear scales compared to a cold dark matter only model, they uncover intriguing insights. Leveraging data from the Dark Energy Survey Year-5 sample, they determine $A_{\rm mod} = 0.77^{+0.69}_{-0.40}$ within a 68% credible interval around the median. While the median aligns with unity, there are indications of potential power suppression with $A_{\rm mod} < 1.09$ at 68% credibility. This investigation sheds light on the complex interplay between cosmological parameters and modifications to the matter power spectrum at non-linear scales, providing valuable insights for refining our understanding of dark energy and cosmic acceleration. The findings underscore the importance of considering a broader range of physical mechanisms beyond traditional models in elucidating the complexities of our universe's evolution.