It is not σ8 : constraining the non-linear matter power spectrum with the Dark Energy Survey Year-5 supernova sample

Shah, P and Davis, T M and Vincenzi, M and Armstrong, P and Brout, D and Camilleri, R and Galbany, L and Gill, M S S and Huterer, D and Jeffrey, N and Lahav, O and Lee, J and Lidman, C and Möller, A and Sullivan, M and Whiteway, L and Wiseman, P and Allam, S and Aguena, M and Annis, J and Blazek, J and Brooks, D and Rosell, A Carnero and Carretero, J and Conselice, C and da Costa, L N and Pereira, M E S and Desai, S and Diehl, H T and Doel, P and Everett, S and Ferrero, I and Flaugher, B and Frieman, J and García-Bellido, J and Gaztanaga, E and Giannini, G and Gruen, D and Gruendl, R A and Gutierrez, G and Hinton, S R and Hollowood, D L and Honscheid, K and James, D J and Lee, S and Marshall, J L and Mena-Fernández, J and Miquel, R and Palmese, A and Pieres, A and Malagón, A A Plazas and Porredon, A and Samuroff, S and Sanchez, E and Sevilla-Noarbe, I and Smith, M and Suchyta, E and Swanson, M E C and Tarle, G and Tucker, D L and Weaverdyck, N and Casas, Ricard and Challis, Pete and Childress, Michael and Covarrubias, Ricardo and D'Andrea, Chris and Filippenko, Alex and Finley, David and Fisher, John and Förster, Francisco and Goldstein, Daniel and González-Gaitán, Santiago and Gupta, Ravi and Hamuy, Mario and Kuhlmann, Steve and Lasker, James and March, Marisa and Marriner, John and Morganson, Eric and Mosher, Jennifer and Swann, Elizabeth and Thomas, Rollin and Wolf, Rachel (2025) It is not σ8 : constraining the non-linear matter power spectrum with the Dark Energy Survey Year-5 supernova sample. Monthly Notices of the Royal Astronomical Society, 537 (4). pp. 3814-3825. ISSN 0035-8711

Abstract

The weak gravitational lensing magnification of Type Ia supernovae (SNe Ia) is sensitive to the matter power spectrum on scales k > 1h Mpc −1, making it unwise to interpret SNe Ia lensing in terms of power on linear scales. We compute the probability density function of SNe Ia magnification as a function of standard cosmological parameters, plus an empirical parameter A mod which describes the suppression or enhancement of matter power on non-linear scales compared to a cold dark matter only model. While baryons are expected to enhance power on the scales relevant to SN Ia lensing, other physics such as neutrino masses or non-standard dark matter may suppress power. Using the Dark Energy Survey Year-5 sample, we find A mod = 0.77 + −0 0 . 40 69 (68 per cent credible interval around the median). Although the median is consistent with unity there are hints of power suppression, with A mod < 1.09 at 68 per cent credibility.