Sweeping Horndeski Canvas: New Growth-Rate Parameterization for Modified-Gravity Theories
| Autor: | Wen, Yuewei, Nguyen, Nhat-Minh, Huterer, Dragan |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | JCAP09(2023)028 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/1475-7516/2023/09/028 |
| Popis: | We propose and numerically validate a new fitting formula that is sufficiently accurate to model the growth of structure in Horndeski theories of modified gravity for upcoming Stage IV and V large-scale structure surveys. Based on an analysis of more than 18,000 Horndeski models and adopting the popular parameterization of the growth rate $f(z) = \Omega_{M}(z)^{\gamma}$, we generalize the constant growth index $\gamma$ to a two-parameter redshift-dependent quantity, $\gamma(z)$, that more accurately fits these models. We demonstrate that the functional form $\gamma(z)=\gamma_0+\gamma_1z^2 / (1+z)$ improves the median $\chi^2$ of the fit to viable Horndeski models by a factor of $\sim40$ relative to that of a constant $\gamma$, and is sufficient to obtain unbiased results even for precise measurements expected in Stage IV and V surveys. Finally, we constrain the parameters of the new fitting formula using current cosmological data. Comment: 23 pages, 6 figures; prepared for JCAP submission; comments welcome! v2: Add missing footnote on author role on the first page; fix latex package rendering error in a section title. v3: Match the version accepted to JCAP; correct repeated references |
| Databáze: | arXiv |
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