A joint microlensing analysis of lensing mass and accretion disc models

TL;DR

This paper introduces a new microlensing modeling approach that independently constrains quasar accretion disc properties and lens parameters, demonstrating robustness across various macromodel assumptions.

Contribution

The paper presents a novel microlensing analysis method that does not rely on the lens macromodel, allowing for more direct and robust measurements of quasar accretion disc characteristics.

Findings

Accretion disc size and temperature profile are robustly measured.

The method can constrain the smooth matter fraction at image locations.

The approach is applicable to multiple systems and data types.

Abstract

Microlensing of multiply imaged quasars is a unique probe of quasar structure, down to the size of the accretion disc and the central black hole. Flux ratios between close pairs of images of lensed quasars can be used to constrain the accretion disc size and temperature profile. The starting point of any microlensing model is the macromodel of the lens, which provides the convergence and shear values at the location of the multiple images. Here I present a new approach of microlensing modelling independently of the macromodel of the lens. The technique is applied to the close pair of images A1 and A2 of MG 0414+0534, for a set of flux ratios with large variation with respect to wavelength. The inferred accretion disc size and temperature profile measurements, as well as the smooth matter fraction at the location of the images, are quite robust under a wide range of macromodel variations. A case of using purely microlensing data (flux ratios) to constrain the macromodel is also presented. This is a first application of the technique on a fiducial system and set of flux ratios; the method is readily applicable to collections of such objects and can be extended to light curve and/or imaging data.