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Exploiting flux ratio anomalies to probe warm dark matter in future large-scale surveys

Harvey, David; Valkenburg, Wessel; Tamone, Amelie; Boyarsky, Alexey; Courbin, Frederic; Lovell, Mark

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Authors

David Harvey

Wessel Valkenburg

Amelie Tamone

Alexey Boyarsky

Frederic Courbin



Abstract

Flux ratio anomalies in strong gravitationally lensed quasars constitute a unique way to probe the abundance of non-luminous dark matter haloes, and hence the nature of dark matter. In this paper, we identify double-imaged quasars as a statistically efficient probe of dark matter, since they are 20 times more abundant than quadruply imaged quasars. Using N-body simulations that include realistic baryonic feedback, we measure the full distribution of flux ratios in doubly imaged quasars for cold (CDM) and warm dark matter (WDM) cosmologies. Through this method, we fold in two key systematics – quasar variability and line-of-sight structures. We find that WDM cosmologies predict a ∼6 per cent difference in the cumulative distribution functions of flux ratios relative to CDM, with CDM predicting many more small ratios. Finally, we estimate that ∼600 doubly imaged quasars will need to be observed in order to be able to unambiguously discern between CDM and the two WDM models studied here. Such sample sizes will be easily within reach of future large-scale surveys such as Euclid. In preparation for this survey data, we require discerning the scale of the uncertainties in modelling lens galaxies and their substructure in simulations, plus a strong understanding of the selection function of observed lensed quasars.

Citation

Harvey, D., Valkenburg, W., Tamone, A., Boyarsky, A., Courbin, F., & Lovell, M. (2020). Exploiting flux ratio anomalies to probe warm dark matter in future large-scale surveys. Monthly Notices of the Royal Astronomical Society, 491(3), 4247-4253. https://doi.org/10.1093/mnras/stz3305

Journal Article Type Article
Acceptance Date Nov 15, 2019
Online Publication Date Nov 29, 2019
Publication Date Jan 31, 2020
Deposit Date Feb 26, 2020
Publicly Available Date Feb 26, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 491
Issue 3
Pages 4247-4253
DOI https://doi.org/10.1093/mnras/stz3305
Public URL https://durham-repository.worktribe.com/output/1275837

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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