The Imprint of Neutrinos on Clustering in Redshift Space

Abstract

We investigate the signatures left by the cosmic neutrino background on the clustering of matter, CDM+baryons and halos in redshift-space using the HADES simulations: a set of more than 1000 N-body and hydrodynamical simulations with massless and massive neutrinos. While on large scales the clustering of matter and CDM+baryons is very different in cosmologies with massive and massless neutrinos, we find that the effect neutrinos induce on the clustering of CDM+baryons in redshift-space on small scales is almost entirely due to the change in σ 8 . However, neutrinos do imprint a characteristic signature in the quadrupole of the total matter field (CDM+baryon+neutrinos) on small scales, that can be used to disentangle the effect of σ 8 and M ν . We show that the effect of neutrinos on the clustering of halos is very different, on all scales, to the effects induced by varying σ 8 . We find that the effects of neutrinos of the growth rate of CDM+baryons ranges from ∼ 0.3% to 2% on scales k ∈ [0.01, 0.5] hMpc −1 for neutrinos with masses M ν 0.15 eV. We compute the bias between the momentum of halos and the momentum of CDM+baryon and find it to be 1 on large scales for all models with massless and massive neutrinos considered. This point towards a velocity bias between halos and total matter on large scales that it is important to account for in order to extract unbiased neutrino information from velocity/momentum surveys such as kSZ observations. We show that, even on very large-scales, non-linear corrections are important to describe the clustering of halos in redshift-space in cosmologies with massless and massive neutrinos at low redshift. We show that baryonic effects can affect the clustering of matter and CDM+baryons in redshift-space by up to a few percent down to k = 0.5 hMpc −1 . We find that hydrodynamics and astrophysical processes, as implemented in our simulations, only distort the relative effect that neutrinos induce on the anisotropic clustering of matter, CDM+baryons and halos in redshift-space by less than 1%. Thus, the effect of neutrinos in the fully non-linear regime can be written as a transfer function with very weak dependence on astrophysics that can be studied through N-body simulations.

Clustering and redshift-space distortions in modified gravity models with massive neutrinos

“…This result also confirms what found by Marulli et al (2012b) for cDE models with massless neutrinos. Similar conclusions have been reached by Villaescusa-Navarro et al (2018), who investigated the redshift-space clustering in massive neutrino cosmologies.…”

Measuring neutrino masses with large-scale structure: Euclid forecast with controlled theoretical error

“…The growth rate in the presence of massive neutrinos has recently been studied with N -body simulations in Ref. [68]. This study showed that the scale-dependence of f is negligible on large scales, where it approaches the value computed for baryons and cold dark matter only.…”

Cosmological parameters and neutrino masses from the final Planck and full-shape BOSS data

“…This prescription was advocated on the basis of N-body simulations in Refs. [62][63][64][65][66]. Furthermore, Refs.…”

“…Assuming the minimal ΛCDM cosmology with massive neutrinos, we find the following late-Universe parameters: the Hubble constant H0 = 67.95 +0. 66 −0.52 km s −1 Mpc −1 , the matter density fraction Ωm = 0.3079 +0.0065 −0.0085 , the mass fluctuation amplitude σ8 = 0.8087 +0.012 −0.0072 , and an upper limit on the sum of neutrino masses Mtot < 0.16 eV (95% CL). This can be contrasted with the Planck-only measurements: H0 = 67.14 +1.…”