Constraining the geometry and kinematics of the quasar broad emission line region using gravitational microlensing

II. Comparing models with observations in the lensed quasar HE0435−1223

¹ Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 19c, B5c, 4000 Liège, Belgium
e-mail: d.hutsemekers@uliege.be
² Observatoire Astronomique de Strasbourg, Université de Strasbourg, Rue de l’Université 11, 67000 Strasbourg, France

Received: 2 May 2017
Accepted: 28 June 2019

Abstract

The quadruply lensed quasar HE0435−1223 shows a clear microlensing effect that affects differently the blue and red wings of the Hα line profile in its image D. To interpret these observations, and constrain the broad emission line region (BLR) properties, the effect of gravitational microlensing on quasar broad emission line profiles and their underlying continuum has been simulated considering representative BLR models and microlensing magnification maps. The amplification and distortion of the Hα line profile, characterized by a set of four indices, can be reproduced by the simulations. Although the constraints on the BLR models set by the observed single-epoch microlensing signal are not very robust, we found that flattened geometries (Keplerian disk and equatorial wind) can more easily reproduce the observed line profile deformations than a biconical polar wind. With an additional independent constraint on the size of the continuum source, the Keplerian disk model of the Hα BLR is slightly favored.