A Lagrangian perturbation theory in the presence of massive neutrinos

Abstract

We develop a Lagrangian Perturbation Theory (LPT) framework to study the clustering of cold dark matter (CDM) in cosmologies with massive neutrinos. We follow the trajectories of CDM particles with Lagrangian displacements fields up to third order in perturbation theory. Once the neutrinos become non-relativistic, their density fluctuations are modeled as being proportional to the CDM density fluctuations, with a scale-dependent proportionality factor. This yields a gravitational back-reaction that introduces additional scales to the linear growth function, which is accounted for in the higher order LPT kernels. Through non-linear mappings from Eulerian to Lagrangian frames, we ensure that our theory has a well behaved large scale behavior free of unwanted UV divergences, which are common when neutrino and CDM densities are not treated on an equal footing, and in resummation schemes that manifestly break Galilean invariance. We use our theory to construct correlation functions for both the underlying matter field, as well as for biased tracers using Convolution-LPT. Redshift-space distortions effects are modeled using the Gaussian Streaming Model. When comparing our analytical results to simulated data from the Quijote 1 simulation suite, we find good accuracy down to r = 20 Mpc h −1 at redshift z = 0.5, for the real space and redshift space monopole particle correlation functions with no free parameters. The same accuracy is reached for the redshift space quadrupole if we additionally consider an

The cosmology dependence of galaxy clustering and lensing from a hybrid N-body–perturbation theory model

“…This increased precision, however, comes at the cost of very large inaccuracies beyond the nonlinear scale at which the self-gravitating dark matter fluid ceases to be perturbative (Blas et al 2014;McQuinn & White 2016). In addition, perturbative frameworks provide a rigorous, first-principles approach to include physics beyond the standard ΛCDM model in large-scale structure observables such as neutrinos, baryonic effects and more exotic early-universe scenarios (Lewandowski et al 2015;Senatore & Zaldarriaga 2017;Aviles & Banerjee 2020;Chen et al 2020c;Laguë et al 2020;Ivanov et al 2020; ? ; .…”

Information content in mean pairwise velocity and mean relative velocity between pairs in a triplet

“…It was found that the mean matter pairwise velocity decreases with increasing neutrino mass at those pair separations. For analytical predictions, Aviles & Banerjee (2020) studied the effect of massive neutrinos on pairwise velocity using Lagrangian perturbation theory for biased tracers at quasi-linear scales and above. The pairwise velocity measurement from kSZ experiments has been shown to be a novel probe to constrain the summed neutrino mass (Mueller et al 2015b), and provide complementary constraints with respect to galaxy clustering and CMB experiments.…”

Holographic dark energy in curved spacetime for interacting fluids

“…The neutrino flavour oscillations provide strong evidence of non null masses for these particles, this fact is also considered as one of the proofs for physics beyond the standard model of particles. However, despite their very small masses they have a non negligible contribution to the total cosmological density at low redshifts playing a relevant role on the formation of large scale structures [39]. The avoidance of clustering of matter inhomogeneities could also be due to the neutrino presence.…”