Parameter sensitivity of cosmic pairwise velocities in the non-linear regime of structure formation
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866916956599222272 |
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| author | García-Farieta, Jorge Enrique Hortúa, Héctor J. |
| author_facet | García-Farieta, Jorge Enrique Hortúa, Héctor J. |
| contents | The peculiar velocities of dark matter tracers drive the growth of cosmic structures, providing a sensitive test of cosmological models and strengthening constraints on the nature of dark energy. In this work, we investigate the mean pairwise velocities, $v_{12}$, of dark matter tracers as a cosmological probe in the non-linear regime of cosmic structure formation. Using N-body dark matter-only simulations, we measure $v_{12}$ for pair separations up to 50 $h^{-1}$Mpc and model it by solving the pair conservation equation for a self-gravitating particle system, along with various prescriptions of the nonlinear matter power spectrum. We quantified the sensitivity of $v_{12}$ to variations in key cosmological parameters such as $Ω_{\mathrm{m}}$, $σ_8$, $h$, $M_ν$, and $w$. Our parameter inference analysis using MCMC shows sub-11% agreement with simulation data, with notable degeneracies, particularly between $Ω_\mathrm{m}$ and $σ_8$. We further compute the stable clustering crossing scale across redshifts $z=0$, $0.5$, and $1$, assessing its dependence on cosmology. Among the tested power spectrum modeling approaches, we find that the CSSTEmu emulator provides the most accurate predictions, with deviations below 5% for $r > 10$ $h^{-1}$Mpc at $z=0.5$. Our results are validated using independent simulation suites, demonstrating that our framework offers a robust method for extracting cosmological constraints from upcoming peculiar velocity data. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2509_15223 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Parameter sensitivity of cosmic pairwise velocities in the non-linear regime of structure formation García-Farieta, Jorge Enrique Hortúa, Héctor J. Cosmology and Nongalactic Astrophysics The peculiar velocities of dark matter tracers drive the growth of cosmic structures, providing a sensitive test of cosmological models and strengthening constraints on the nature of dark energy. In this work, we investigate the mean pairwise velocities, $v_{12}$, of dark matter tracers as a cosmological probe in the non-linear regime of cosmic structure formation. Using N-body dark matter-only simulations, we measure $v_{12}$ for pair separations up to 50 $h^{-1}$Mpc and model it by solving the pair conservation equation for a self-gravitating particle system, along with various prescriptions of the nonlinear matter power spectrum. We quantified the sensitivity of $v_{12}$ to variations in key cosmological parameters such as $Ω_{\mathrm{m}}$, $σ_8$, $h$, $M_ν$, and $w$. Our parameter inference analysis using MCMC shows sub-11% agreement with simulation data, with notable degeneracies, particularly between $Ω_\mathrm{m}$ and $σ_8$. We further compute the stable clustering crossing scale across redshifts $z=0$, $0.5$, and $1$, assessing its dependence on cosmology. Among the tested power spectrum modeling approaches, we find that the CSSTEmu emulator provides the most accurate predictions, with deviations below 5% for $r > 10$ $h^{-1}$Mpc at $z=0.5$. Our results are validated using independent simulation suites, demonstrating that our framework offers a robust method for extracting cosmological constraints from upcoming peculiar velocity data. |
| title | Parameter sensitivity of cosmic pairwise velocities in the non-linear regime of structure formation |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2509.15223 |