The effects of non-linearity on the growth rate constraint from velocity correlation functions
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866910354589614080 |
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| author | Tonegawa, Motonari Appleby, Stephen Park, Changbom Hong, Sungwook E. Kim, Juhan |
| author_facet | Tonegawa, Motonari Appleby, Stephen Park, Changbom Hong, Sungwook E. Kim, Juhan |
| contents | The two-point statistics of the cosmic velocity field, measured from galaxy peculiar velocity (PV) surveys, can be used as a dynamical probe to constrain the growth rate of large-scale structures in the universe. Most works use the statistics on scales down to a few tens of Megaparsecs, while using a theoretical template based on the linear theory. In addition, while the cosmic velocity is volume-weighted, the observable line-of-sight velocity two-point correlation is density-weighted, as sampled by galaxies, and therefore the density-velocity correlation term also contributes, which has often been neglected. These effects are fourth order in powers of the linear density fluctuation $δ_{\rm L}^4$, compared to $δ_{\rm L}^2$ of the linear velocity correlation function, and have the opposite sign. We present these terms up to $δ_{\rm L}^4$ in real space based on the standard perturbation theory, and investigate the effect of non-linearity and the density-velocity contribution on the inferred growth rate $fσ_8$, using $N$-body simulations. We find that for a next-generation PV survey of volume $\sim {\cal O}(500 \, h^{-1} \, {\rm Mpc})^3$, these effects amount to a shift of $fσ_8$ by $\sim 10$ per cent and is comparable to the forecasted statistical error when the minimum scale used for parameter estimation is $r_{\rm min} = 20 \, h^{-1} \, {\rm Mpc}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2309_14457 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | The effects of non-linearity on the growth rate constraint from velocity correlation functions Tonegawa, Motonari Appleby, Stephen Park, Changbom Hong, Sungwook E. Kim, Juhan Cosmology and Nongalactic Astrophysics The two-point statistics of the cosmic velocity field, measured from galaxy peculiar velocity (PV) surveys, can be used as a dynamical probe to constrain the growth rate of large-scale structures in the universe. Most works use the statistics on scales down to a few tens of Megaparsecs, while using a theoretical template based on the linear theory. In addition, while the cosmic velocity is volume-weighted, the observable line-of-sight velocity two-point correlation is density-weighted, as sampled by galaxies, and therefore the density-velocity correlation term also contributes, which has often been neglected. These effects are fourth order in powers of the linear density fluctuation $δ_{\rm L}^4$, compared to $δ_{\rm L}^2$ of the linear velocity correlation function, and have the opposite sign. We present these terms up to $δ_{\rm L}^4$ in real space based on the standard perturbation theory, and investigate the effect of non-linearity and the density-velocity contribution on the inferred growth rate $fσ_8$, using $N$-body simulations. We find that for a next-generation PV survey of volume $\sim {\cal O}(500 \, h^{-1} \, {\rm Mpc})^3$, these effects amount to a shift of $fσ_8$ by $\sim 10$ per cent and is comparable to the forecasted statistical error when the minimum scale used for parameter estimation is $r_{\rm min} = 20 \, h^{-1} \, {\rm Mpc}$. |
| title | The effects of non-linearity on the growth rate constraint from velocity correlation functions |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2309.14457 |