Galaxy Cluster Bulk Flows and Collision Velocities in QUMOND

TL;DR

This study explores galaxy cluster formation in a QUMOND cosmology with sterile neutrinos, revealing higher velocities and earlier formation times compared to standard bcbd, aligning better with observations.

Contribution

It introduces numerical simulations of galaxy clusters in QUMOND with sterile neutrinos, highlighting differences from bcbd, especially in velocities and formation times.

Findings

Clusters reach ~1000 km/s bulk velocities at low redshift.

High pairwise velocities are common in cluster collisions.

Massive clusters tend to form earlier and be larger in QUMOND.

Abstract

We examine the formation of clusters of galaxies in numerical simulations of a QUMOND cosmogony with massive sterile neutrinos. Clusters formed in these exploratory simulations develop higher velocities than those found in {\Lambda}CDM simulations. The bulk motions of clusters attain about 1000 km/s by low redshift, comparable to observations whereas {\Lambda}CDM simulated clusters tend to fall short. Similarly, high pairwise velocities are common in cluster-cluster collisions like the Bullet cluster. There is also a propensity for the most massive clusters to be larger in QUMOND and to appear earlier than in {\Lambda}CDM, potentially providing an explanation for 'pink elephants' like El Gordo. However, it is not obvious that the cluster mass function can be recovered.