He, Q. and Li, R. and Lim, S. and Frenk, C. S. and Cole, S. and Peng, E. W. and Wang, Q. (2018) 'Globular clusters versus dark matter haloes in strong lensing observations.', Monthly notices of the Royal Astronomical Society., 480 (4). pp. 5084-5091.
Small distortions in the images of Einstein rings or giant arcs offer the exciting prospect of detecting low mass dark matter haloes or subhaloes of mass below 109 M⊙ (for independent haloes, the mass refers to M200, and for subhaloes, the mass refers to the mass within tidal radius), most of which are too small to have made a visible galaxy. A very large number of such haloes are predicted to exist in the cold dark matter model of cosmogony; in contrast, other models, such as warm dark matter, predict no haloes below a mass of this order, which depends on the properties of the warm dark matter particle. Attempting to detect these small perturbers could therefore discriminate between different kinds of dark matter particles, and even rule out the cold dark matter model altogether. Globular clusters in the lens galaxy also induce distortions in the image, which could, in principle, contaminate the test. Here, we investigate the population of globular clusters in six early-type galaxies in the Virgo cluster. We find that the number density of globular clusters of mass MGC ∼ 106 M⊙ is comparable to that of the dark matter perturbers (subhaloes in the lenses and haloes along the line of sight of comparable mass). We show that the very different degrees of mass concentration in globular clusters and dark matter haloes result in different lensing distortions. These are detectable with milli-arcsecond resolution imaging, which can distinguish between globular cluster and dark matter halo signals.
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|Publisher Web site:||https://doi.org/10.1093/mnras/sty2260|
|Publisher statement:||This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.|
|Date accepted:||14 August 2018|
|Date deposited:||25 September 2018|
|Date of first online publication:||18 August 2018|
|Date first made open access:||25 September 2018|
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