Improved analytical modeling of the non-linear power spectrum in modified gravity cosmologies
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arXiv
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| Natura: | Preprint |
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2023
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| author | Gupta, Suhani Hellwing, Wojciech A. Bilicki, Maciej |
| author_facet | Gupta, Suhani Hellwing, Wojciech A. Bilicki, Maciej |
| contents | Reliable analytical modeling of the non-linear power spectrum (PS) of matter perturbations is among the chief pre-requisites for cosmological analyses from the largest sky surveys. This is especially true for the models that extend the standard general-relativity paradigm by adding the fifth force, where numerical simulations can be prohibitively expensive. Here we present a method for building accurate PS models for two modified gravity (MG) variants: namely the Hu-Sawicki $f(R)$, and the normal branch of the Dvali-Gabadadze-Porrati (nDGP) braneworld. We start by modifying the standard halo model (HM) with respect to the baseline Lambda-Cold-Dark-Matter ($Λ$CDM) scenario, by using the HM components with specific MG extensions. We find that our $P(k)_{\text{HM}}$ retains 5% accuracy only up to mildly non-linear scales ($k \lesssim 0.3$ $h/\,\mbox{Mpc}$) when compared to PS from numerical simulations. At the same time, our HM prescription much more accurately captures the ratio $Υ(k) = P(k)_{\text{MG}}/P(k)_{Λ\text{CDM}}$ up to non-linear scales. We show that using HM-derived $Υ(k)$ together with a viable non-linear $Λ$CDM $P(k)$ prescription (such as HALOFIT), we render a much better and more accurate PS predictions in MG. The new approach yields considerably improved performance, with modeled $P(k)_{\text{MG}}$ being now accurate to within 5% all the way to non-linear scales of $k \lesssim 2.5-3$ $h/\,\mbox{Mpc}$. The magnitude of deviations from GR as fostered by these MG models is typically $\mathcal{O}(10\%)$ in these regimes. Therefore reaching 5% PS modeling is enough for forecasting constraints on modern-era cosmological observables. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2301_12016 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Improved analytical modeling of the non-linear power spectrum in modified gravity cosmologies Gupta, Suhani Hellwing, Wojciech A. Bilicki, Maciej Cosmology and Nongalactic Astrophysics Reliable analytical modeling of the non-linear power spectrum (PS) of matter perturbations is among the chief pre-requisites for cosmological analyses from the largest sky surveys. This is especially true for the models that extend the standard general-relativity paradigm by adding the fifth force, where numerical simulations can be prohibitively expensive. Here we present a method for building accurate PS models for two modified gravity (MG) variants: namely the Hu-Sawicki $f(R)$, and the normal branch of the Dvali-Gabadadze-Porrati (nDGP) braneworld. We start by modifying the standard halo model (HM) with respect to the baseline Lambda-Cold-Dark-Matter ($Λ$CDM) scenario, by using the HM components with specific MG extensions. We find that our $P(k)_{\text{HM}}$ retains 5% accuracy only up to mildly non-linear scales ($k \lesssim 0.3$ $h/\,\mbox{Mpc}$) when compared to PS from numerical simulations. At the same time, our HM prescription much more accurately captures the ratio $Υ(k) = P(k)_{\text{MG}}/P(k)_{Λ\text{CDM}}$ up to non-linear scales. We show that using HM-derived $Υ(k)$ together with a viable non-linear $Λ$CDM $P(k)$ prescription (such as HALOFIT), we render a much better and more accurate PS predictions in MG. The new approach yields considerably improved performance, with modeled $P(k)_{\text{MG}}$ being now accurate to within 5% all the way to non-linear scales of $k \lesssim 2.5-3$ $h/\,\mbox{Mpc}$. The magnitude of deviations from GR as fostered by these MG models is typically $\mathcal{O}(10\%)$ in these regimes. Therefore reaching 5% PS modeling is enough for forecasting constraints on modern-era cosmological observables. |
| title | Improved analytical modeling of the non-linear power spectrum in modified gravity cosmologies |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2301.12016 |