An excess of small-scale gravitational lenses observed in galaxy clusters
Abstract
Cold dark matter (CDM) constitutes most of the matter in the Universe. The interplay between dark and luminous matter in dense cosmic environments like galaxy clusters is studied theoretically using cosmological simulations. Observed gravitational lensing is used to test and characterize the properties of substructures - the small-scale distribution of dark matter - in clusters. An apt metric, the probability of strong lensing events produced by dark matter substructure, is devised and computed for 11 galaxy clusters. We report that observed cluster substructures are more efficient lenses than predicted by CDM simulations, by more than an order of magnitude. We suggest that hitherto undiagnosed systematic issues with simulations or incorrect assumptions about the properties of dark matter could explain our results.
Keywords
Cite
@article{arxiv.2009.04471,
title = {An excess of small-scale gravitational lenses observed in galaxy clusters},
author = {Massimo Meneghetti and Guido Davoli and Pietro Bergamini and Piero Rosati and Priyamvada Natarajan and Carlo Giocoli and Gabriel B. Caminha and R. Benton Metcalf and Elena Rasia and Stefano Borgani and Francesco Calura and Claudio Grillo and Amata Mercurio and Eros Vanzella},
journal= {arXiv preprint arXiv:2009.04471},
year = {2020}
}
Comments
56 pages, 15 figures. Published in Science