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Virial theorem in clusters of galaxies with MOND

López-Corredoira, M; Betancort-Rijo, JE; Scarpa, R; Chrobáková, Z; (2022) Virial theorem in clusters of galaxies with MOND. Monthly Notices of the Royal Astronomical Society , 517 (4) pp. 5734-5743. 10.1093/mnras/stac3117. Green open access

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Abstract

A specific modification of Newtonian dynamics known as MOND has been shown to reproduce the dynamics of most astrophysical systems at different scales without invoking non-baryonic dark matter (DM). There is, however, a long-standing unsolved problem when MOND is applied to rich clusters of galaxies in the form of a deficit (by a factor around two) of predicted dynamical mass derived from the virial theorem with respect to observations. In this article, we approach the virial theorem using the velocity dispersion of cluster members along the line of sight rather than using the cluster temperature from X-ray data and hydrostatic equilibrium. Analytical calculations of the virial theorem in clusters for Newtonian gravity + DM and MOND are developed, applying pressure (surface) corrections for non-closed systems. Recent calibrations of DM profiles, baryonic ratio, and baryonic (β model or others) profiles are used, while allowing free parameters to range within the observational constraints. It is shown that solutions exist for MOND in clusters that give similar results to Newton + DM - particularly in the case of an isothermal β model for β = 0.55-0.70 and core radii rc between 0.1 and 0.3 times r500 (in agreement with the known data). The disagreements found in previous studies seem to be due to the lack of pressure corrections (based on inappropriate hydrostatic equilibrium assumptions) and/or inappropriate parameters for the baryonic matter profiles.

Type: Article
Title: Virial theorem in clusters of galaxies with MOND
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/stac3117
Publisher version: https://doi.org/10.1093/mnras/stac3117
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: gravitation, galaxies: clusters, dark matter
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery-pp.ucl.ac.uk/id/eprint/10202954
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