Abstract
Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In particular microlensing reveals the intrinsic absorption hidden in the P Cygni-type line profiles observed in the broad absorption line quasar H1413+117, as well as the existence of an extended continuum source. In addition, polarization microlensing provides constraints on the scattering region. In the quasar Q2237+030, microlensing differently distorts the H$\alpha$ and CIV broad emission line profiles, indicating that the low- and high-ionization broad emission lines must originate from regions with distinct kinematical properties. We also present simulations of the effect of microlensing on line profiles considering simple but representative models of the broad emission line region. Comparison of observations to simulations allows us to conclude that the H$\alpha$ emitting region in Q2237+030 is best represented by a Keplerian disk.
Highlights
When the light from a distant quasar passes through the gravitational field of a galaxy, it is deflected and multiple magnified images of the source are observed
FMμ) partially filled in by the broad emission line; (2) this absorption does not start at zero-velocity but at an onset velocity of ∼2,000 km/s; (3) the broad emission line itself is reabsorbed over a wavelength range narrower than the full absorption profile, revealing the existence of an additional, more extended BALR; (4) a part of the continuum is not microlensed originating from a region larger than the source of the continuum seen in FMμ
Recent results from velocity-resolved reverberation mapping suggest that the low-ionization BELR can be a Keplerian disk (Grier et al, 2017, and references therein). These results demonstrate the potential of microlensing to probe the geometry and kinematics of the broad line regions and outflows in quasars
Summary
When the light from a distant quasar passes through the gravitational field of a galaxy, it is deflected and multiple magnified images of the source are observed. FMμ) partially filled in by the broad emission line (seen in FM); (2) this absorption does not start at zero-velocity but at an onset velocity of ∼2,000 km/s; (3) the broad emission line itself is reabsorbed (see FM) over a wavelength range narrower than the full absorption profile, revealing the existence of an additional, more extended BALR; (4) a part of the continuum (seen in FM) is not microlensed originating from a region larger than the source of the continuum seen in FMμ These observations suggest a two-component outflow: one component is co-spatial with the BELR, while the other one, more distant, partially re-absorbs the emission from the BELR (Borguet and Hutsemékers, 2010). This indicates that the non-microlensed extended continuum seen in FM (Figure 1) could originate from scattering
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