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تسجيل مستخدم جديدRevealing the structure of the lensed quasar Q 0957+561: III. SMBH mass via gravitational redshift
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We intend to use the impact of microlensing on the Fe III emission line blend along with a measure of its gravitational redshift to estimate the mass of the quasars central supermassive black hole (SMBH). We fit the Fe III feature in multiple spectroscopic observations between 2008 and 2016 of the gravitationally lensed quasar Q 0957+561 with relatively high signal-to-noise ratios (at the adequate wavelength). Based on the statistics of microlensing magnifications, we used a Bayesian method to derive the size of its emitting region. The Fe III spectral feature appears systematically redshifted in all epochs of observation by a value of 17 angstroms on average. We find clear differences in the shape of the Fe III line blend between images A and B. Measuring the strength of those magnitude differences, we conclude that this blend may arise from a region of half-light radius of 15 lt-days, which is in good agreement with the accretion disk dimensions for this system. We obtain a mass for the central SMBH of (1.5 +/- 0.5) x 10^9 solar masses, consistent within uncertainties with previous mass estimates based on the virial theorem. The relatively small uncertainties in the mass determination (< 35%) make this method a compelling alternative to other existing techniques (e.g., the virial plus reverberation mapping based size) for measuring black hole masses. Combining the Fe III redshift-based method with the virial, we estimate a virial factor in the 1.2 to 1.7 range for this system.
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We aim to use signatures of microlensing induced by stars in the foreground lens galaxy to infer the size of the accretion disk in the gravitationally lensed quasar Q 0957+561. The long-term photometric monitoring of this system (which so far has pro
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Knowledge about how the nonlinear behaviour of the intrinsic signal from lensed background sources changes on its path to the observer provides much information, particularly about the matter distribution in lensing galaxies and the physical properti
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