Light Curves of Lensed Components and Time Delay Measurements in the Binary Gravtationally Lensed Quasars SDSS J2124\(+\)1632 and SDSS J0806\(+\)2006

Abstract

The article presents the results of long-term photometric monitoring of two binary gravitationally lensed quasars, SDSS J2124\(+\)1632 and SDSS J0806\(+\)2006, carried out at the Maidanak Observatory in 2017–2022. The obtained light curves of the lensed components of both systems are analyzed. The variability of SDSS J2124\(+\)1632 turned out to be quite large: up to \(0\overset{\textrm{m}}{.}50\) for the system as a whole and up to \(0\overset{\textrm{m}}{.}75\) for component A. Long-term microlensing was found against the background of a general increase in the apparent brightness of the quasar source. The brightness variations in SDSS J0806\(+\)2006 are less intense: the range is about \(0\overset{\textrm{m}}{.}20\) for the system as a whole, and up to \(0\overset{\textrm{m}}{.}25\) for both components. Analysis of the light curves did not show the presence of microlensing here. We also calculated the probable values of the time delay: \(\Delta t_{\textrm{AB}}=102\pm 20\) days (component B is in the lead) and \(\Delta t_{\textrm{AB}}=-53.0\pm 6.0\) days (component A is in the lead) in SDSS J2124\(+\)1632 and SDSS J0806\(+\)2006, respectively. The value of \(\Delta t_{\textrm{AB}}\) for SDSS J2124\(+\)1632 is consistent with previously found time delays for binary gravitationally lensed systems. In the case of the second system, the time delay is consistent with earlier theoretical calculations, which suggested that the time delay should be about 50 days.