Disentangling Modified Gravity and Massive Neutrinos with Intrinsic Shape Alignments of Massive Halos

Abstract

Two new diagnostics to break the dark sector degeneracy based on the intrinsic shape alignments of group/cluster size dark matter halos are presented. Using the snapshot data from a series of the DUSTGRAIN-pathfinder N-body simulations for the Planck ΛCDM cosmology and three f (R) gravity models with massive neutrinos (ν), we first determine the probability density functions of the alignment angles between the shape orientations of massive halos and the minor principal axes of the local tidal fields. The numerically obtained results turn out to agree very well with the analytic formula derived under the assumption that the anisotropic merging along the cosmic web induces the halo shape alignments. The four cosmologies, which several standard diagnostics failed to discriminate, are found to yield significantly different best-fit values of the single parameter that characterizes the analytic formula. We also numerically determine the spatial cross-correlations between the shape orientations of neighbor group/cluster halos, and find them to be in good agreements with a fitting formula characterized by two parameters, whose best-fit values are found to substantially differ among the four models. It is concluded that our new diagnostics can disentangle the effect of f (R) gravity from that of massive neutrinos on the occurrence of anisotropic merging along the cosmic web, which is believed to originate the intrinsic shape alignments of massive halos.

Combined Effects of f(R) Gravity and Massive Neutrinos on the Turnaround Radii of Dark Matter Halos

“…The DUSTGRAIN-pathfinder simulation project aimed at keeping track of 768 3 CDM particles of individual mass 8.1 × 10 10 h −1 M e under the influence of f (R) gravity in the presence of massive neutrinos (Giocoli et al 2018) For each of the four models, i.e., the ΛCDM and the three νCDM+f (R) gravity cosmologies, Lee et al (2022) identified the DM halos by applying the Rockstar algorithm (Behroozi et al 2013) to the snapshot data of the DUSTGRAINpathfinder simulations. From the Rockstar halo catalogs at z = 0, we extract the cluster-size distinct halos with M v 4.05 × 10 13 h −1 M e enclosing 500 or more DM particles within their virial radii r v .…”

Updated neutrino mass constraints from galaxy clustering and CMB lensing-galaxy cross-correlation measurements

“…[168][169][170][171][172][173][174][175][176][177]), as well as related cosmological observables (see e.g. [178][179][180][181][182][183][184][185][186][187][188][189][190]).…”