Modified Baryonic Dynamics: two-component cosmological simulations with light sterile neutrinos

TL;DR

This paper tests a modified cosmological model called Modified Baryonic Dynamics, combining MOND with sterile neutrinos, using two-component simulations to address galaxy cluster formation issues, but finds it fails to match observed cluster mass functions.

Contribution

It introduces a new two-component simulation approach where baryons and sterile neutrinos produce different gravitational fields in a MOND framework.

Findings

Fails to reproduce the observed galaxy cluster mass function

Attenuates over-production of galaxy clusters compared to previous models

Highlights theoretical challenges of Modified Baryonic Dynamics

Abstract

In this article we continue to test cosmological models centred on Modified Newtonian Dynamics (MOND) with light sterile neutrinos, which could in principle be a way to solve the fine-tuning problems of the standard model on galaxy scales while preserving successful predictions on larger scales. Due to previous failures of the simple MOND cosmological model, here we test a speculative model where the modified gravitational field is produced only by the baryons and the sterile neutrinos produce a purely Newtonian field (hence Modified Baryonic Dynamics). We use two component cosmological simulations to separate the baryonic N-body particles from the sterile neutrino ones. The premise is to attenuate the over-production of massive galaxy cluster halos which were prevalent in the original MOND plus light sterile neutrinos scenario. Theoretical issues with such a formulation notwithstanding, the Modified Baryonic Dynamics model fails to produce the correct amplitude for the galaxy cluster mass function for any reasonable value of the primordial power spectrum normalisation.