DEMNUni: the Sunyaev-Zel'dovich effect in the presence of massive neutrinos and dynamical dark energy

Abstract

In recent years, the study of secondary anisotropies in the Cosmic Microwave Background has become a fundamental instrument to test our understanding of the Universe. Using a set of lightcones produced with the ``Dark Energy and Massive Neutrino Universe'' $N$-body simulations, we study how different dark energy equations of state and neutrino masses impact the properties of the thermal Sunyaev-Zel'dovich (tSZ) effect, focusing on the signal arising from galaxy clusters and groups. We analyse the distribution of values for the Compton-$y$ parameter and study its angular power spectrum. We find that the distribution of the logarithmic Compton parameter can be fitted with a skewed Gaussian, with a mean that, at fixed dark energy model, decreases linearly with an approximate slope of $10 f_\nu$. Regarding the power spectrum of the thermal SZ effect, we find that an increase in $\sum {m_\nu}$ is observed as a power-law scaling with respect to $\sigma_8^{\mathrm{cb}}$, with exponents ranging from 7.3 to 8.1. We also find that models with massless neutrinos typically overestimate Compton-$y$ data extracted from Planck measurements; a better agreement with the simulations is obtained for $\sum m_\nu = 0.16$ or $\sum m_\nu=0.32$ eV. For all the \texttt{DEMNUni} models we forecast the cumulative signal-to-noise ratio for thermal SZ observations with the LAT instrument of the Simons Observatory; furthermore, we compute a tailored $\chi_\mathrm{SNR}^2$ estimator to infer if such models can be distinguished from the reference $\Lambda$CDM.