Speaker
Description
Accurate modeling of small-scale redshift-space clustering is crucial for full-shape RSD analyses, where satellite galaxies contribute to 1-halo terms and Finger-of-God distortions. We study halo reconstruction with the cylinder-grouping method of Okumura et al. (2017), which selects an effective halo-center tracer from the observed galaxy distribution. Using DESI-like LRG mocks from AbacusSummit $N$-body simulations at $z=1.1$, we perform EFT-based fits to the power-spectrum multipoles within the ShapeFit framework.
We show that the main reconstruction-induced systematics can be consistently handled within the same EFT likelihood. In particular, the dominant large-scale effect is captured by a simple multipole-dependent rescaling measured directly from the data, while residual small-scale changes are absorbed by the standard counterterm and stochastic sectors without introducing reconstruction-specific parameters. Compared to galaxy-based fits, the reconstructed sample yields more stable constraints on all ShapeFit parameters as $k_{\max}$ is increased. In particular, the inferred $f\sigma_8$ remains consistent with the fiducial cosmology beyond $k_{\max}\simeq 0.2\,h\,{\rm Mpc}^{-1}$, where the galaxy-based result begins to drift. At higher $k_{\max}$, reconstruction reduces the $1\sigma$ uncertainty on $f\sigma_8$ by $\gtrsim 20\%$ relative to the galaxy case.
| Participate the oral/poster presentation award competition | No |
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