paper

Redshift-space galaxy bispectrum in presence of massive neutrinos: A multipole expansion approach for Euclid

arXiv:2505.01270 · doi:10.1093/mnras/staf1218

Abstract

Massive neutrinos imprint distinctive signatures on the evolution of cosmic structures, notably suppressing small-scale clustering. We investigate the impact of massive neutrinos on the galaxy bispectrum in redshift-space, adopting a spherical harmonic multipole decomposition , that captures the full angular dependence. We develop an analytical and numerical framework incorporating neutrino-corrected perturbation theory kernels and redshift-space distortions. Our results demonstrate that the linear triangle configurations are particularly sensitive to massive neutrinos, with deviations reaching up to for a total mass . To assess detection prospects in galaxy surveys like \textit{Euclid}, we compute the signal-to-noise ratio (SNR) for individual multipoles, including the effects of Finger-of-God damping and shot noise. The neutrino-induced signatures in and are found to be detectable with SNR across a range of configurations, even after accounting for small-scale suppression. Higher-order multipoles such as and are moderately sensitive, with SNR () in squeezed limits, while hexadecapole moments are more suppressed but still exhibit measurable signals at high . Additionally, the SNR generally increases with wave number , particularly for squeezed and stretched triangles, suggesting that access to smaller scales significantly enhances detection prospects. Our study highlights the potential of the redshift-space bispectrum multipoles as sensitive probes of massive neutrinos, complementing traditional power spectrum analyses, and underscores the importance of angular information and higher-order statistics for galaxy surveys.

18 pages, 11 figures. Effects of tidal bias are added in the revised version. Appeared in MNRAS. Comments are welcome

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