The kinematic Sunyaev–Zel’dovich effect of the large-scale structure (I): dependence on neutrino mass

Abstract

The study of neutrinos in astrophysics requires the combination of different observational probes. The temperature anisotropies of the cosmic microwave background induced via the kinematic Sunyaev-Zel'dovich (kSZ) effect may provide interesting information since they are expected to receive significant contribution from high-redshift plasma. We present a set of cosmological hydrodynamical simulations that include a treatment of the neutrino component considering four different sum of neutrino masses: Σm ν = (0, 0.15, 0.3, 0.6) eV. Using their outputs, we modelled the kSZ effect due to the large-scale structure after the reionization by producing mock maps, then computed the kSZ power spectrum and studied how it depends on z re and Σm ν . We also run a set of four simulations to study and correct possible systematics due to resolution, finite box size and astrophysics. With massless neutrinos we obtain D kSZ 3000 = 4.0 µK 2 (z re =8.8), enough to account for all of the kSZ signal of D kSZ 3000 = (2.9 ± 1.3) µK 2 measured with the South Pole Telescope. This translates into an upper limit on the kSZ effect due to patchy reionization of D kSZ,patchy 3000 < 1.0 µK 2 (95 per cent confidence level). Massive neutrinos induce a damping of kSZ effect power of about 8, 12 and 40 per cent for Σm ν = (0.15, 0.3, 0.6) eV, respectively. We study the dependence of the kSZ signal with z re and the neutrino mass fraction, f ν , and obtain D kSZ 3000 ∝z re 0.26 (1 − f ν ) 14.3 . Interestingly, the scaling with f ν is significantly shallower with respect to the equivalent thermal SZ effect, and may be used to break the degeneracy with other cosmological parameters. 1 This limit applies in the case of normal hierarchy, for the inverted hierarchy the limit is Σm ν > 0.1 eV. 2012Lesgourgues et al. 2013; Gonzalez-Garcia 2014, and references therein).From the astrophysical point of view, the existence of massive neutrinos influences the evolution of the large-scale structure (LSS) formation via gravitational interaction, thus requiring a generalization of the standard Λ cold dark matter (ΛCDM) cosmological model to account for Σm ν as an additional free parameter, leading to a ΛCDMν scenario. The effect of this new component is twofold. On early times it contributes to the Universe energy budget as radiation, with density of ρ ν = 7 8 4 11where ρ γ is the photon energy density, and N eff is the effective number of neutrino species (N eff = 3.046, according to the SM). This causes a postponing of the matter-radiation equality for a fixed value of Ω m h 2 (where Ω m is the ratio between the total matter denc 2016 RAS

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