Origin of Chromatic Features in Multiple Quasars -Variability, Dust, or Microlensing - AstrophysicsReport as inadecuate




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Abstract: Aims:In some of the lensed quasars, color differences between multiple imagesare observed at optical-near-infrared wavelengths. There are three possibleorigins of the color differences: intrinsic variabilities of quasars,differential dust extinction, and quasar microlensing. We examine how thesethree possible scenarios can reproduce the observed chromaticity. Methods:Weevaluate how much color difference between multiple images can be reproduced bythe above three possible scenarios with realistic models; i an empiricalrelation for intrinsic variabilities of quasars, ii empirical relations fordust extinction and theoretically predicted inhomogeneity in galaxies, or iiia theoretical model for quasar accretion disks and magnification patterns inthe vicinity of caustics. Results:We find that intrinsic variabilities ofquasars cannot be a dominant source responsible for observed chromatic featuresin multiple quasars. In contrast, either dust extinction or quasar microlensingcan nicely reproduce the observed color differences between multiple images inmost of the lensed quasars. Taking into account the time interval betweenobservations at different wavebands in our estimations, quasar microlensing isa more realistic scenario to reproduce the observed color differences than dustextinction. All the observed color differences presented in this paper can beexplained by a combination of these two effects, but monitoring observations atmultiple wavebands are necessary to disentangle these.



Author: Atsunori Yonehara, Hiroyuki Hirashita, Philipp Richter

Source: https://arxiv.org/



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