Volume 592, August 2016
|Number of page(s)||10|
|Published online||06 July 2016|
The different origins of high- and low-ionization broad emission lines revealed by gravitational microlensing in the Einstein cross⋆
1 Institut d’Astrophysique, Université de Liège, Allée du 6 Août 17, B5c, 4000 Liège, Belgium
2 Departamento de Ciencias Fisicas, Universidad Andres Bello, Av. Republica 252, Santiago, Chile
3 Millennium Institute of Astrophysics, 1515 Las Condes, Santiago, Chile
Received: 25 March 2016
Accepted: 11 May 2016
We investigate the kinematics and ionization structure of the broad emission line region of the gravitationally lensed quasar QSO2237+0305 (the Einstein cross) using differential microlensing in the high- and low-ionization broad emission lines. We combine visible and near-infrared spectra of the four images of the lensed quasar and detect a large-amplitude microlensing effect distorting the high-ionization CIV and low-ionization Hα line profiles in image A. While microlensing only magnifies the red wing of the Balmer line, it symmetrically magnifies the wings of the CIV emission line. Given that the same microlensing pattern magnifies both the high- and low-ionization broad emission line regions, these dissimilar distortions of the line profiles suggest that the high- and low-ionization regions are governed by different kinematics. Since this quasar is likely viewed at intermediate inclination, we argue that the differential magnification of the blue and red wings of Hα favors a flattened, virialized, low-ionization region whereas the symmetric microlensing effect measured in CIV can be reproduced by an emission line formed in a polar wind, without the need of fine-tuned caustic configurations.
Key words: quasars: individual: Einstein cross / quasars: emission lines
© ESO, 2016
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