On simple analytic models of microlensing amplification statistics
EntityUAM. Departamento de Física Teórica
10.1016/j.dark.2020.100567Physics of the Dark Universe 29 (2020): 100567
Funded byPF received the support of a fellowship from ‘‘la Caixa’’ Foundation, Spain (ID 100010434). The fellowship code is LCF/BQ/PI19/11690018. JGB thanks the CERN TH-Division for hospitality during his sabbatical, when this project was initiated, and acknowledges support from the Research Project FPA2015-68048-03-3P [MINECO-FEDER] and the Centro de Excelencia Severo Ochoa Program SEV-2012-0597. He also acknowledges support from the Salvador de Madariaga Program, Ref. PRX17/00056
ProjectGobierno de España. FPA2015-68048-03-3P; Gobierno de España. SEV-2012-0597
SubjectsGravitational Lenses; Quasars; Galaxies; Física
Rights© 2020 Published by Elsevier B.V.
Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
Gravitational microlensing is a key probe of the nature of dark matter and its distribution on the smallest scales. For many practical purposes, confronting theory to observation requires to model the probability that a light source is highly amplified by many-lens systems. This article reviews four simple analytic models of the amplification probability distribution, based on different approximations: (i) the strongest-lens model; (ii) the multiplicative model, where the total amplification is assumed to be the product of all the lenses’ individual amplifications; (iii) a hybrid version of the previous two; and (iv) an empirical fitting function. In particular, a new derivation of the multiplicative amplification distribution is proposed, thereby correcting errors in the literature. Finally, the accuracy of these models is tested against ray-shooting simulations. They all produce excellent results as long as lenses are light and rare (low optical depth); however, for larger optical depths, none of them succeeds in capturing the relevant features of the amplification distribution. This conclusion emphasizes the crucial role of lens–lens coupling at large optical depths
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