Aletheia: Emulating the non-linear matter power spectrum in the context of evolution mapping
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2025
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| author | Sanchez, Ariel G. Ruiz, Andrés N. Rodriguez, Facundo Correa, Carlos Fiorilli, Andrea Esposito, Matteo Gonzalez-Jara, Jenny Padilla, Nelson D. Pérez-Fernández, Alejandro Contarini, Sofia |
| author_facet | Sanchez, Ariel G. Ruiz, Andrés N. Rodriguez, Facundo Correa, Carlos Fiorilli, Andrea Esposito, Matteo Gonzalez-Jara, Jenny Padilla, Nelson D. Pérez-Fernández, Alejandro Contarini, Sofia |
| contents | We present Aletheia, a new emulator of the non-linear matter power spectrum, $P(k)$, built upon the evolution mapping framework. This framework addresses the limitations of traditional emulation by focusing on $h$-independent cosmological parameters, which can be separated into those defining the linear power spectrum shape ($\mathbfΘ_{\mathrm{s}}$) and those affecting only its amplitude evolution ($\mathbfΘ_{\mathrm{e}}$). The combined impact of evolution parameters and redshift is compressed into a single amplitude parameter, $σ_{12}$. Aletheia uses a two-stage Gaussian Process emulation: a primary emulator predicts the non-linear boost factor as a function of ($\mathbfΘ_{\mathrm{s}}$) and $σ_{12}$ for fixed evolution parameters, while a second one applies a small linear correction based on the integrated growth history. The emulator is trained on shape parameters spanning $\pm$5$σ$ of Planck constraints and a wide clustering range $0.2 < σ_{12} < 1.0$, providing predictions for $0.006\,{\rm Mpc}^{-1} < k < 2\,{\rm Mpc}^{-1}$. We validate Aletheia against N-body simulations, demonstrating sub-percent accuracy. When tested on a suite of dynamic dark energy models, the full emulator's predictions show a variance of approximately 0.2%, a factor of five smaller than that of the state-of-the-art EuclidEmulator2 (around 1% variance). Furthermore, Aletheia maintains sub-percent accuracy for the best-fit dynamic dark energy cosmology from recent DESI data, a model whose parameters lie outside the training ranges of most conventional emulators. This demonstrates the power of the evolution mapping approach, providing a robust and extensible tool for precision cosmology. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_13826 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Aletheia: Emulating the non-linear matter power spectrum in the context of evolution mapping Sanchez, Ariel G. Ruiz, Andrés N. Rodriguez, Facundo Correa, Carlos Fiorilli, Andrea Esposito, Matteo Gonzalez-Jara, Jenny Padilla, Nelson D. Pérez-Fernández, Alejandro Contarini, Sofia Cosmology and Nongalactic Astrophysics We present Aletheia, a new emulator of the non-linear matter power spectrum, $P(k)$, built upon the evolution mapping framework. This framework addresses the limitations of traditional emulation by focusing on $h$-independent cosmological parameters, which can be separated into those defining the linear power spectrum shape ($\mathbfΘ_{\mathrm{s}}$) and those affecting only its amplitude evolution ($\mathbfΘ_{\mathrm{e}}$). The combined impact of evolution parameters and redshift is compressed into a single amplitude parameter, $σ_{12}$. Aletheia uses a two-stage Gaussian Process emulation: a primary emulator predicts the non-linear boost factor as a function of ($\mathbfΘ_{\mathrm{s}}$) and $σ_{12}$ for fixed evolution parameters, while a second one applies a small linear correction based on the integrated growth history. The emulator is trained on shape parameters spanning $\pm$5$σ$ of Planck constraints and a wide clustering range $0.2 < σ_{12} < 1.0$, providing predictions for $0.006\,{\rm Mpc}^{-1} < k < 2\,{\rm Mpc}^{-1}$. We validate Aletheia against N-body simulations, demonstrating sub-percent accuracy. When tested on a suite of dynamic dark energy models, the full emulator's predictions show a variance of approximately 0.2%, a factor of five smaller than that of the state-of-the-art EuclidEmulator2 (around 1% variance). Furthermore, Aletheia maintains sub-percent accuracy for the best-fit dynamic dark energy cosmology from recent DESI data, a model whose parameters lie outside the training ranges of most conventional emulators. This demonstrates the power of the evolution mapping approach, providing a robust and extensible tool for precision cosmology. |
| title | Aletheia: Emulating the non-linear matter power spectrum in the context of evolution mapping |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2511.13826 |