Microlensing probes the AGN structure of the lensed quasar J1131-1231

TL;DR

This study uses microlensing effects observed in a gravitationally lensed quasar to investigate the structure of its broad emission line region, revealing details about emission regions and absorption features.

Contribution

First observational evidence of differential microlensing of broad emission lines in a lensed quasar, providing insights into the BLR structure and emission regions.

Findings

Anti-correlation between emission line width and emitting region size

FeII emission occurs in both outer and compact BLR regions

Insights into the origin of narrow MgII absorption doublet

Abstract

We present the analysis of single epoch long slit spectra of the three brightest images of the gravitationally lensed system J1131-1231. These spectra provide one of the clearest observational evidence for differential micro-lensing of broad emission lines (BELs) in a gravitationally lensed quasar. The micro-lensing effect enables us: (1) to confirm that the width of the emission lines is anti-correlated to the size of the emitting region; (2) to show that the bulk of FeII is emitted in the outer parts of the Broad Line Region (BLR) while another fraction of FeII is produced in a compact region; (3) to derive interesting informations on the origin of the narrow intrinsic MgII absorption doublet observed in that system.