High-resolution imaging follow-up of doubly imaged quasars

May 2021 • 2021MNRAS.503.1557S

Authors • Shajib, Anowar J. • Molina, Eden • Agnello, Adriano • Williams, Peter R. • Birrer, Simon • Treu, Tommaso • Fassnacht, Christopher D. • Morishita, Takahiro • Abramson, Louis • Schechter, Paul L. • Wisotzki, Lutz

Abstract • We report upon 3 years of follow-up and confirmation of doubly imaged quasar lenses through imaging campaigns from 2016 to 2018 with the Near-Infrared Camera2 (NIRC2) on the W. M. Keck Observatory. A sample of 57 quasar lens candidates are imaged in adaptive-optics-assisted or seeing-limited K'-band observations. Out of these 57 candidates, 15 are confirmed as lenses. We form a sample of 20 lenses adding in a number of previously known lenses that were imaged with NIRC2 in 2013-14 as part of a pilot study. By modelling these 20 lenses, we obtain K'-band relative photometry and astrometry of the quasar images and the lens galaxy. We also provide the lens properties and predicted time delays to aid planning of follow-up observations necessary for various astrophysical applications, e.g. spectroscopic follow-up to obtain the deflector redshifts for the newly confirmed systems. We compare the departure of the observed flux ratios from the smooth-model predictions between doubly and quadruply imaged quasar systems. We find that the departure is consistent between these two types of lenses if the modelling uncertainty is comparable.


IPAC Authors


Takahiro Morishita

Assistant Scientist