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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 607166.0, MPI für Astronomie / Publikationen_mpia
Zooming into the broad line region of the gravitationally lensed quasar QSO 2237 + 0305 ≡ the Einstein Cross. III. Determination of the size and structure of the Civ and Ciii] emitting regions using microlensing
Authors:Sluse, D.; Schmidt, R.; Courbin, F.; Hutsemékers, D.; Meylan, G.; Eigenbrod, A.; Anguita, T.; Agol, E.; Wambsganss, J.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:Astronomy and Astrophysics
Audience:Not Specified
Abstract / Description:<BR /> Aims: We aim to use microlensing taking place in the lensed quasar QSO 2237 + 0305 to study the structure of the broad line region (BLR) and measure the size of the region emitting the C iv and C iii] lines. <BR /> Methods: Based on 39 spectrophotometric monitoring data points obtained between Oct. 2004 and Dec. 2007, we derived lightcurves for the C iv and C iii] emission lines. We used three different techniques to analyse the microlensing signal. Different components of the lines (narrow, broad, and very broad) were identified and studied. We built a library of the simulated microlensing lightcurves that reproduce the signal observed in the continuum and in the lines provided only the source size is changed. A Bayesian analysis scheme is then developed to derive the size of the various components of the BLR. <BR /> Results: 1. The half-light radius of the region emitting the C iv line is found to be RC IV} Ëœ 66+110-46} light-days = 0.06+0.09-0.04 pc = 1.7+2.8-1.1 × 1017 cm (at 68.3% CI). Similar values are obtained for C iii]. Relative sizes of the carbon-line and V-band continuum emitting-regions are also derived with median values of Rline/Rcont in the range 4 to 29, depending on the FWHM of the line component. 2. The size of the C iv emitting region agrees with the radius-luminosity relationship derived from reverberation mapping. Using the virial theorem, we derive the mass of the black hole in QSO 2237 + 0305 to be MBH ~ 108.3 ± 0.3 M&sun;. 3. We find that the C iv and C iii] lines are produced in at least 2 spatially distinct regions, the most compact one giving rise to the broadest component of the line. The broad and narrow line profiles are slightly different for C iv and C iii]. 4. Our analysis suggests a different structure for the C iv and Fe ii+iii emitting regions, with the latter produced in the inner part of the BLR or in a less extended emitting region than C iv. Based on observations made with the ESO-VLT Unit Telescope # 2 Kueyen (Cerro Paranal, Chile; Proposals 073.B-0243(A&B), 074.B-0270(A), 075.B-0350(A), 076.B-0197(A), 177.B-0615(A&B), PI: F. Courbin).
Free Keywords:gravitational lensing: micro; gravitational lensing: strong; quasars: general; quasars: emission lines; quasars: individual: QSO 2237 + 0305; line: formation
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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