LELANTOS — Large-scalE LymAN-alpha TOmography Suite

LELANTOS — Greek titan associated with hunting and air (name found after discussion with E. Chaussidon).

Package to create and manipulate large-scale Lyman-α tomographic maps.

It takes the flux-contrast files (delta) produced by picca, converts them into the input of a tomographic solver, runs the reconstruction, and post-processes the resulting 3D map into line-of-sight (pixel) products, tomographic maps, void catalogs and diagnostic plots. Every stage can be run on its own (via a launcher, a script or the API) or all at once through a single configuration file.

📖 Full documentation (API reference + user guide): https://corentinravoux.github.io/lelantos/

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Pipeline overview

picca deltas ──DeltaConverter──▶ pixel binary ──TomographyManager──▶ tomographic map
                                                     (Dachshund)              │
                                                                              ├─▶ VoidFinder ──▶ void catalog ──▶ stacks / QSO-like x-corr catalog
                                                                              └─▶ map & delta plots

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Install

This package can be installed with pip:

pip install . --user

The minimal required python packages are: fitsio, numpy, scipy, matplotlib, picca (installed automatically with pip).

To convert a tomographic box into a format for 3D visualization, you need pyevtk as an additional package.

This package uses code parts from the public packages picca and SaclayMocks — it is advised to install them independently (a vendored SaclayMocks fallback ships under lelantos/saclaymocks/).

To run tomographic mapping, place the executable of the tomographic algorithm you want to use in the lelantos/lelantos/exec directory. For now the only algorithm available is dachshund.

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Running the whole pipeline

Most of the launchers below can be run in one go by editing a configuration file and running:

lelantos_interface.py interface_example.ini

• scripts/interface_example.ini — a ready-to-edit example.
• scripts/interface_explanatory.ini — a fully commented reference that documents every option and whether it is mandatory or optional.

The [main] section is a switchboard of booleans, one per stage; each stage reads its own config section. See the documentation Pipeline & config page for the full description.

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Launchers

The main launchers available in the launchers/ folder are:

• lelantos_subsample_delta.py — Subsampling of flux-contrast files (delta), output of the picca delta generation routine.
• lelantos_shuffle_delta.py — Shuffling of flux-contrast files (delta).
• lelantos_convert_delta.py — Conversion of flux-contrast files (delta) to a pixel file, input of the tomographic mapping procedure.
• lelantos_tomography_manager.py — Running the tomography algorithm.
• lelantos_tomography_process.py — Processing the tomographic map output.
• lelantos_void_finder.py — Launching the void-finding routine on the tomographic map.
• lelantos_void_process.py — Post-processing of the void catalog.
• lelantos_plot_delta.py — Plotting routines for flux-contrast files (delta).
• lelantos_plot_pixel.py — Plotting routines for the pixel file.
• lelantos_plot_tomography.py — Plotting routines for the tomographic map.
• lelantos_plot_void.py — Plotting routines for the void catalog.

Additional launchers for specific studies:

• lelantos_stack_void.py — Stacking of void positions on a tomographic map.
• lelantos_stack_qso.py — Stacking of quasar positions on a tomographic map.
• lelantos_plot_stack_void.py — Plotting routines for the void stack.
• lelantos_plot_stack_qso.py — Plotting routines for the QSO stack.
• lelantos_tomography_3d.py — Conversion of tomographic objects into a format for 3D visualization.
• lelantos_boxdm.py — Extraction of the underlying dark-matter box of mocks associated with a given box geometry.

Each launcher is configured by editing the variables at the top of the file, then running it directly (python launchers/<name>.py).

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Scripts

The scripts/ folder contains small utilities using argparse or a config parser to quickly modify or show information about tomographic objects (print a property file, cut a QSO/DLA catalog, show void statistics, estimate a map shape/size, …), plus lelantos_interface.py for the full pipeline.

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Package modules

Module	Role
lelantos.cosmology	Delta ingestion, shuffling/subsampling, solver-input generation, delta/pixel diagnostics
lelantos.tomographic_objects	Core data objects: maps, distance maps, stacks, pixels, deltas, property files, catalogs
lelantos.task_manager	Run the tomographic solver locally (bash) or on a cluster (NERSC / Irene)
lelantos.tomography	Map post-processing, slice/histogram plots, stacking
lelantos.voidfinder	Spherical / watershed void detection and post-processing
lelantos.boxdm	Extract the underlying SaclayMocks dark-matter field onto a map geometry
lelantos.utils	Coordinate transforms, interpolation, plotting, logging helpers
lelantos.interface	Config-file driven end-to-end pipeline

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Conventions

• RA / Dec handled in radians internally (degrees at the plotting boundary); comoving distances and box sizes in Mpc·h⁻¹; wavenumbers in h/Mpc.
• The sky ↔ cartesian transform is chosen per run via coordinate_transform (middle, full_angle/full, cartesian); most downstream code assumes the middle tangent-plane transform.
• The fiducial cosmology enters only at delta conversion, through Omega_m.

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Documentation

📖 Online: https://corentinravoux.github.io/lelantos/

Documentation is written with MkDocs Material and mkdocstrings (the API reference is generated from the in-code docstrings) and is published to GitHub Pages by the .github/workflows/docs.yml workflow on every push to main (enable Settings → Pages → Source: GitHub Actions once).

Build it locally with:

pip install -r requirements-docs.txt
mkdocs serve      # live preview at http://127.0.0.1:8000
mkdocs build      # static site into site/