lyapower

lyapower fits the three-dimensional flux power spectrum P₃D(k, μ) of the Lyman-alpha forest measured from Nyx hydrodynamical simulations (post-processed by the gimlet code), implementing the non-linear models of Arinyo-i-Prats et al. 2015 and the splicing technique that combines simulation boxes of different resolution.

It lets you:

• read gimlet / genpk / ascii power-spectrum files as MatterPowerSpectrum / FluxPowerSpectrum objects, rebin and plot them (power_spectra);
• compute the linear matter power spectrum with CLASS or cosmoprimo (CLASS);
• fit the flux P₃D with the Arinyo non-linear models (D0, D1, and BAO variants) using iminuit (fitter);
• splice low- and high-resolution boxes into a single P(k) / P(k, μ) (power_spectra).

Where lyapower sits

lyapower is a Pillar 2 (estimators) analysis package: it turns simulated Lyman-alpha flux fields into a fitted 3D flux power spectrum and its Arinyo model parameters.

flowchart LR
    A["Nyx simulation"] --> B["gimlet<br/>P3D(k, mu) / P(k)"]
    B --> C["power_spectra<br/>read / rebin / splice"]
    D["CLASS / cosmoprimo<br/>linear P(k)"] --> E["fitter<br/>Arinyo model fit"]
    C --> E
    E --> F["b, beta + non-linear params"]

Quick look

from lyapower import power_spectra

flux = power_spectra.FluxPowerSpectrum.init_3D_from_gimlet(
    "data_example/plt00216z_flux_pkmu.txt", type_file="txt", kmu=True,
)
k, mu = flux.k_array          # stacked [k, mu], in h/Mpc and mu = k_par/k
p = flux.power_array

Next steps

• Getting started — install and read a first spectrum.
• Analysis pipeline — from simulation to fitted P₃D.
• API reference — every module, class and function.

Conventions

Wavenumbers k are in h/Mpc (see change_k_normalization for the 1/Mpc case), mu = k_parallel / k, and power spectra are P(k) (1D) or P(k, μ) (3D, with k_array stacked as [k, mu]).