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Observable tests of self-interacting dark matter in galaxy clusters : cosmological simulations with SIDM and baryons.

Robertson, Andrew and Harvey, David and Massey, Richard and Eke, Vincent and McCarthy, Ian G. and Jauzac, Mathilde and Li, Baojiu and Schaye, Joop (2019) 'Observable tests of self-interacting dark matter in galaxy clusters : cosmological simulations with SIDM and baryons.', Monthly notices of the Royal Astronomical Society., 488 (3). pp. 3646-3662.


We present BAHAMAS-SIDM, the first large-volume, (400 h−1 Mpc)3, cosmological simulations including both self-interacting dark matter (SIDM) and baryonic physics. These simulations are important for two primary reasons: 1) they include the effects of baryons on the dark matter distribution 2) the baryon particles can be used to make mock observables that can be compared directly with observations. As is well known, SIDM haloes are systematically less dense in their centres, and rounder, than CDM haloes. Here we find that that these changes are not reflected in the distribution of gas or stars within galaxy clusters, or in their X-ray luminosities. However, gravitational lensing observables can discriminate between DM models, and we present a menu of tests that future surveys could use to measure the SIDM interaction strength. We ray-trace our simulated galaxy clusters to produce strong lensing maps. Including baryons boosts the lensing strength of clusters that produce no critical curves in SIDM-only simulations. Comparing the Einstein radii of our simulated clusters with those observed in the CLASH survey, we find that at velocities around 1000 km s−1 an SIDM cross-section of σ/m ≳ 1 cm2 g−1 is likely incompatible with observed cluster lensing.

Item Type:Article
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Publisher statement:© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
Date accepted:12 October 2018
Date deposited:18 July 2019
Date of first online publication:10 July 2019
Date first made open access:No date available

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