CoLoRe-2LPT: Lyman- alpha mock catalogues for the validation of DESI cosmological analyses

arXiv:2607.27412 · astro-ph.CO · Submitted 2026-07-29 · Read on arXiv

M. F. Ruiz-Herrera Bernal, S. Avila, A. Font-Ribera, H. K. Herrera-Alcantar, D. Alonso, A. Cuceu, L. Casas, F. Sinigaglia, J. Aguilar, S. Ahlen, O. Alves, U. Andrade, E. Armengaud, A. Bault, F. Beutler, D. Bianchi, M. Bonici, A. Brodzeller, D. Brooks, A. Carnero Rosell, J. Chaves-Montero, Z. Chen, Y. Cho, T. Claybaugh, K. S. Dawson, A. de la Macorra, A. Dey, W. Elbers, S. Ferraro, J. E. Forero-Romero, G. Gambardella, S. Gontcho A Gontcho, D. Gonzalez, A. X. Gonzalez-Morales, C. Gordon, R. Gsponer, G. Gutierrez, J. Guy, C. Hahn, M. Herbold, K. Honscheid, M. Ishak, S. Jos, S. Juneau, N. V. Kamble, T. Karim, D. Kirkby, A. Kremin, M. Landriau, A. Leauthaud, Q. Li, W. Liu, K. Lodha, O. Manasoiu, M. Manera, P. Martini, A. Meisner, R. Miquel, J. Morawetz, P. Mukherjee, A. Muñoz-Gutiérrez, S. Nadathur, G. Niz, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, J. Pan, M. Pellejero Ibanez, W. J. Percival, C. Poppett, F. Prada, H. Pulido-Hernández, A. Pérez-Fernández, I. Pérez-Ràfols, C. Ravoux, J. Rohlf, G. Rossi, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, H. Seo, J. Silber, T. Simon, M. Siudek, G. Tarlé, W. Turner, R. Vaisakh, M. Vargas-Magaña, B. A. Weaver, H. Yang, H. Zhang

astro-ph.CO

Submitted: 2026-07-29

Comments: 17 pages, 11 figures, 2 tables, submitted to A&A

Code: https://github.com/damonge/CoLoRe

License: http://creativecommons.org/licenses/by/4.0/

The gist: The Lyman- alpha (Ly alpha) forest has become a crucial probe for studying the large-scale structure of the universe at high redshift (z > 2), providing powerful constraints on Baryon Acoustic

Terminology

Abstract

The Lyman- alpha (Ly alpha) forest has become a crucial probe for studying the large-scale structure of the universe at high redshift (z > 2), providing powerful constraints on Baryon Acoustic Oscillations (BAO) and the full-shape (FS) clustering of matter. As a key ingredient for upcoming BAO and FS analyses, we present a new generation of fast cosmological Ly alpha mocks based on second-order Lagrangian perturbation theory (2LPT). These new mocks significantly improve upon previous log-normal approaches, both at accurately capturing small scale clustering and at recovering the non-linear broadening of the BAO peak. They are able to reproduce Ly alpha statistics within 10% of the latest DESI measurement; including the Ly alpha bias and the redshift-space distortion beta parameter, mean transmitted flux, and 1D power spectrum. The corresponding quasar (QSO) clustering is also improved with respect to previous approaches, calibrated against high-resolution Abacus simulations, recovering the observational QSO linear bias to less than 5% and improving redshift-space distortions via 2LPT velocities and the addition of Fingers-of-God effects. Furthermore, these mocks incorporate high column density systems and metal lines, allowing us to explore the effects and systematics induced by these astrophysical contaminants. This new set of mocks has been key for enhancing the modeling and validation of the DESI DR2 Ly alpha full shape cosmological analysis. This work provides a physically motivated and computationally efficient tool for simulating current and next-generation Ly alpha surveys and validating FS and BAO analysis.

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