Time-domain studies of gravitationally lensed quasars (GLQs)

TL;DR

This study uses seven years of optical and near-infrared monitoring data of seven gravitationally lensed quasars to analyze intrinsic and extrinsic brightness variations, enabling insights into black hole regions and lensing galaxy properties.

Contribution

It provides high-quality light curves of GLQs over seven years, demonstrating their use in disentangling intrinsic/extrinsic variations and in reverberation mapping and redshift estimation.

Findings

Disentangled intrinsic and extrinsic brightness variations in GLQs.

Successfully performed reverberation mapping of accretion disks.

Estimated redshifts of lensing galaxies using time-domain data.

Abstract

We present the overview and current results of an ongoing optical/NIR monitoring of seven GLQs with the 2-m Liverpool Robotic Telescope. The photometric data over the first seven years of this programme (2005-2011) are leading to high-quality light curves, which in turn are being used as key tools for different standard and novel studies. While brightness records of non-lensed distant quasars may contain unrecognized extrinsic variations, one can disentangle intrinsic from extrinsic signal in certain GLQs. Thus, some GLQs in our sample allow us to assess their extrinsic and intrinsic variations, as well as to discuss the origin of both kinds of fluctuations. We also demonstrate the usefulness of GLQ time-domain data to obtain successful reverberation maps of inner regions of accretion disks around distant supermassive black holes, and to estimate redshifts of distant lensing galaxies.