What question did this study set out to answer?

The study aims to resolve the Lyman-alpha forest tension within the self-interacting fuzzy dark matter framework by adjusting the matter transfer function and boson mass.

May 21, 2026Open Access

Resolving the Lyman-alpha Tension in the Guerrero si-FDM Framework: Self-Interaction Correction to the Matter Transfer Function and Effective Boson Mass Mapping

Key Points

The study aims to resolve the Lyman-alpha forest tension within the self-interacting fuzzy dark matter framework by adjusting the matter transfer function and boson mass.
Implemented non-linear self-interaction coupling derived from the infrared fixed point of the renormalization group flow.
Computed the corrected cosmological matter transfer function, adjusting for effective boson mass and the half-power suppression scale.
Formulated predictions for the 1D flux power spectrum based on upcoming high-resolution data.
Achieved a +97.6% shift in the half-power suppression scale from k_{1/2} = 12.8 Mpc^{-1} to k_{1/2} = 25.3 Mpc^{-1}.
Mapped the effective non-interacting boson mass to m_{22,eff} ≈ 37.0, complying with intergalactic transmission limits.
Provided measurable predictions for the flux power spectrum down to k ≈ 25-50 Mpc^{-1}.

Abstract

We present the formal cosmological resolution of the Lyman-alpha (\ Lyman-) forest tension within the Guerrero self-interacting Fuzzy Dark Matter (si-FDM) framework. Standard non-interacting FDM models suffer from a fundamental paradox: the low boson mass required to solve small-scale galactic core challenges (m₂₂ 1–8) severely underpredicts the power spectrum of the high-redshift intergalactic medium, violating observational constraints that enforce m₂₂ > 20 (Iršič et al. 2017). By implementing the non-linear attractive self-interaction coupling (g₍₋ = 0. 00597) derived deterministically from the infrared fixed point of the renormalization group flow (Paper 2, ₈ₑ = 0. 5094), we compute the corrected cosmological matter transfer function T ₒ₈ (k). The attractive term provides an effective structural rigidity that shifts the half-power suppression scale from k₁/₂ = 12. 8 Mpc^-1 (free FDM) to k₁/₂ = 25. 3 Mpc^-1 for a physical mass of m₂₂ = 8. This outstanding +97. 6% shift maps analytically to an effective non-interacting boson mass of m₂₂, ₄₅₅ 37. 0, placing the framework in full compliance with conservative intergalactic transmission limits without any parameter fine-tuning. We demonstrate why historical free-field bounds (e. g. , Rogers & Peiris 2021) are systematically inapplicable to this architecture due to modified velocity field dynamics. Finally, we formulate an explicit, quantitative prediction for the 1D flux power spectrum down to k 25–50 Mpc^-1 to be tested by upcoming high-resolution data from the Dark Energy Spectroscopic Instrument (DESI).

Resolving the Lyman-alpha Tension in the Guerrero si-FDM Framework: Self-Interaction Correction to the Matter Transfer Function and Effective Boson Mass Mapping

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Abstract

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