Emulating the Lyman-Alpha forest 1D power spectrum from cosmological simulations: New models and constraints from the eBOSS measurement
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| Auteurs principaux: | , , , , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866910990836170752 |
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| author | Walther, Michael Schöneberg, Nils Chabanier, Solène Armengaud, Eric Sexton, Jean Yèche, Christophe Lesgourgues, Julien Mosbech, Markus R. Ravoux, Corentin Palanque-Delabrouille, Nathalie Lukić, Zarija |
| author_facet | Walther, Michael Schöneberg, Nils Chabanier, Solène Armengaud, Eric Sexton, Jean Yèche, Christophe Lesgourgues, Julien Mosbech, Markus R. Ravoux, Corentin Palanque-Delabrouille, Nathalie Lukić, Zarija |
| contents | We present the Lyssa suite of high-resolution cosmological simulations of the Lyman-$α$ forest designed for cosmological analyses. These 18 simulations have been run using the Nyx code with $4096^3$ hydrodynamical cells in a 120 Mpc ($\sim$ 81Mpc/h) comoving box and individually provide sub-percent level convergence of the Lyman-$α$ forest 1d flux power spectrum. We build a Gaussian process emulator for the Lyssa simulations in the lym1d likelihood framework to interpolate the power spectrum at arbitrary parameter values. We validate this emulator based on leave-one-out tests and based on the parameter constraints for simulations outside of the training set. We also perform comparisons with a previous emulator, showing a percent level accuracy and a good recovery of the expected cosmological parameters. Using this emulator we derive constraints on the linear matter power spectrum amplitude and slope parameters $A_{\mathrm{Ly}α}$ and $n_{\mathrm{Ly}α}$. While the best-fit Planck $Λ$CDM model has $A_{\mathrm{Ly}α}=8.79$ and $n_{\mathrm{Ly}α}=-2.363$, from DR14 eBOSS data we find that $A_{\mathrm{Ly}α}<7.6$ (95\% CI) and $n_{\mathrm{Ly}α}=-2.369 \pm 0.008$. The low value of $A_{\mathrm{Ly}α}$, in tension with Planck, is driven by the correlation of this parameter with the mean transmission of the Lyman-$α$ forest. This tension disappears when imposing a well-motivated external prior on this mean transmission, in which case we find $A_{\mathrm{Ly}α}=9.8\pm1.1$ in accordance with Planck. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_05372 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Emulating the Lyman-Alpha forest 1D power spectrum from cosmological simulations: New models and constraints from the eBOSS measurement Walther, Michael Schöneberg, Nils Chabanier, Solène Armengaud, Eric Sexton, Jean Yèche, Christophe Lesgourgues, Julien Mosbech, Markus R. Ravoux, Corentin Palanque-Delabrouille, Nathalie Lukić, Zarija Cosmology and Nongalactic Astrophysics We present the Lyssa suite of high-resolution cosmological simulations of the Lyman-$α$ forest designed for cosmological analyses. These 18 simulations have been run using the Nyx code with $4096^3$ hydrodynamical cells in a 120 Mpc ($\sim$ 81Mpc/h) comoving box and individually provide sub-percent level convergence of the Lyman-$α$ forest 1d flux power spectrum. We build a Gaussian process emulator for the Lyssa simulations in the lym1d likelihood framework to interpolate the power spectrum at arbitrary parameter values. We validate this emulator based on leave-one-out tests and based on the parameter constraints for simulations outside of the training set. We also perform comparisons with a previous emulator, showing a percent level accuracy and a good recovery of the expected cosmological parameters. Using this emulator we derive constraints on the linear matter power spectrum amplitude and slope parameters $A_{\mathrm{Ly}α}$ and $n_{\mathrm{Ly}α}$. While the best-fit Planck $Λ$CDM model has $A_{\mathrm{Ly}α}=8.79$ and $n_{\mathrm{Ly}α}=-2.363$, from DR14 eBOSS data we find that $A_{\mathrm{Ly}α}<7.6$ (95\% CI) and $n_{\mathrm{Ly}α}=-2.369 \pm 0.008$. The low value of $A_{\mathrm{Ly}α}$, in tension with Planck, is driven by the correlation of this parameter with the mean transmission of the Lyman-$α$ forest. This tension disappears when imposing a well-motivated external prior on this mean transmission, in which case we find $A_{\mathrm{Ly}α}=9.8\pm1.1$ in accordance with Planck. |
| title | Emulating the Lyman-Alpha forest 1D power spectrum from cosmological simulations: New models and constraints from the eBOSS measurement |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2412.05372 |