Non-linear CMB lensing with neutrinos and baryons: FLAMINGO simulations versus fast approximations

Upadhye, Amol; Kwan, Juliana; McCarthy, Ian G; Salcido, Jaime; Helly, John C; Kugel, Roi; Schaller, Matthieu; Schaye, Joop; Braspenning, Joey; Elbers, Willem; Frenk, Carlos S; van Daalen, Marcel P; Vandenbroucke, Bert; Broxterman, Jeger C

Abstract

Weak lensing of the cosmic microwave background is rapidly emerging as a powerful probe of neutrinos, dark energy, and new
physics. We present a fast computation of the non-linear CMB lensing power spectrum that combines non-linear perturbation
theory at early times with powerspectrum emulation using cosmologicalsimulations at late times.Comparing our calculation with
light-cones from the FLAMINGO 5.6 Gpc cube dark-matter-only simulation, we confirm its accuracy to 1 per cent (2 per cent)
up to multipoles L = 3000 (L = 5000) for a νCDM cosmology consistent with current data. Clustering suppression due to
small-scale baryonic phenomena such as feedback from active galactic nuclei can reduce the lensing power by ∼ 10 per cent.
To our perturbation theory and emulator-based calculation, we add SP(k), a new fitting function for this suppression, and
confirm its accuracy compared to the FLAMINGO hydrodynamic simulations to 4 per cent at L = 5000, with similar accuracy for
massive neutrino models. We further demonstrate that scale-dependent suppression due to neutrinos and baryons approximately
factorize, implying that a careful treatment of baryonic feedback can limit biasing neutrino mass constraints.

Citation

Upadhye, A., Kwan, J., McCarthy, I. G., Salcido, J., Helly, J. C., Kugel, R., …Broxterman, J. C. (2024). Non-linear CMB lensing with neutrinos and baryons: FLAMINGO simulations versus fast approximations. Monthly Notices of the Royal Astronomical Society, 529(2), 1862-1876. https://doi.org/10.1093/mnras/stae663

• Journal Article Type: Article
• Acceptance Date: Mar 2, 2024
• Online Publication Date: Mar 7, 2024
• Publication Date: 2024-04
• Deposit Date: May 22, 2024
• Publicly Available Date: May 22, 2024
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 529
• Issue: 2
• Pages: 1862-1876
• DOI: https://doi.org/10.1093/mnras/stae663
• Public URL: https://durham-repository.worktribe.com/output/2455753