An excess of small-scale gravitational lenses observed in galaxy clusters

Massimo Meneghetti; Guido Davoli; Pietro Bergamini; Piero Rosati; Priyamvada Natarajan; Carlo Giocoli; Gabriel B Caminha; R Benton Metcalf; Elena Rasia; Stefano Borgani; Francesco Calura; Claudio Grillo; Amata Mercurio; Eros Vanzella

doi:10.1126/science.aax5164

An excess of small-scale gravitational lenses observed in galaxy clusters

Science. 2020 Sep 11;369(6509):1347-1351. doi: 10.1126/science.aax5164.

Authors

Massimo Meneghetti^{1

2

3}, Guido Davoli^{4

5}, Pietro Bergamini⁴, Piero Rosati^{6

4}, Priyamvada Natarajan⁷, Carlo Giocoli^{4

6

8}, Gabriel B Caminha⁹, R Benton Metcalf⁸, Elena Rasia^{10

11}, Stefano Borgani^{10

11

12

13}, Francesco Calura⁴, Claudio Grillo^{14

15}, Amata Mercurio¹⁶, Eros Vanzella⁴

Affiliations

¹ Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Istituto Nazionale di Astrofisica Via Gobetti 93/3, I-40129, Bologna, Italy. massimo.meneghetti@inaf.it.
² National Institute for Nuclear Physics, viale Berti Pichat 6/2, I-40127 Bologna, Italy.
³ Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA.
⁴ Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Istituto Nazionale di Astrofisica Via Gobetti 93/3, I-40129, Bologna, Italy.
⁵ Centro Euro-Mediterraneo sui Cambiamenti Climatici (CMCC), viale Berti Pichat 6/2, I-40127 Bologna, Italy.
⁶ Dipartimento di Fisica e Scienza della Terra, Università di Ferrara, via Saragat 1, I-44122 Ferrara, Italy.
⁷ Department of Astronomy, 52 Hillhouse Avenue, Steinbach Hall, Yale University, New Haven, CT 06511, USA.
⁸ Dipartimento di Fisica e Astronomia, Università di Bologna, via Gobetti 93/2, 40129 Bologna, Italy.
⁹ Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, Netherlands.
¹⁰ Osservatorio Astronomico di Trieste, Istituto Nazionale di Astrofisica, Via Tiepolo, 11, I-34131 Trieste, Italy.
¹¹ Institute for Fundamental Physics of the Universe, Via Beirut 2, 34014 Trieste, Italy.
¹² Department of Physics, University of Trieste, via Tiepolo 11, I-34131 Trieste, Italy.
¹³ National Institute for Nuclear Physics, Via Valerio 2, I-34127 Trieste, Italy.
¹⁴ Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, I-20133 Milano, Italy.
¹⁵ Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, 4. sal 2100 Copenhagen, Denmark.
¹⁶ Osservatorio Astronomico di Capodimonte, Istituto Nazionale di Astrofisica, Salita Moiariello, 16, I-80131 Napoli, Italy.

PMID: 32913099
DOI: 10.1126/science.aax5164

Abstract

Cold dark matter (CDM) constitutes most of the matter in the Universe. The interplay between dark and luminous matter in dense cosmic environments, such as galaxy clusters, is studied theoretically using cosmological simulations. Observations of gravitational lensing are used to characterize the properties of substructures-the small-scale distribution of dark matter-in clusters. We derive a metric, the probability of strong lensing events produced by dark-matter substructure, and compute it for 11 galaxy clusters. The observed cluster substructures are more efficient lenses than predicted by CDM simulations, by more than an order of magnitude. We suggest that systematic issues with simulations or incorrect assumptions about the properties of dark matter could explain our results.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.