Radio Monitoring Campaigns of Six Strongly Lensed Quasars

TL;DR

This study monitored six strongly lensed radio quasars to assess their variability and suitability for cosmological measurements via time delays, finding significant variability in most systems but no direct delay measurements.

Contribution

First comprehensive radio monitoring of six lensed quasars to evaluate their potential for cosmological parameter estimation through time delay analysis.

Findings

Most systems showed intrinsic variability.

B0712 and B1030 exhibited strong linear flux variations.

Follow-up campaigns are recommended for promising systems.

Abstract

We observed six strongly lensed, radio-loud quasars (MG 0414+0534, CLASS B0712+472, JVAS B1030+074, CLASS B1127+385, CLASS B1152+199, and JVAS B1938+666) in order to identify systems suitable for measuring cosmological parameters using time delays between their multiple images. These systems are in standard two and four image configurations, with B1938 having a faint secondary pair of images. Two separate monitoring campaigns were carried out using the VLA and upgraded JVLA. Lightcurves were extracted for each individual lensed image and analyzed for signs of intrinsic variability. While it was not possible to measure time delays from these data, $\chi^2$-based and structure function tests found evidence for variability in a majority of the lightcurves. B0712 and B1030 had particularly strong variations, exhibiting linear flux trends. These results show that most of these systems should be targeted with followup monitoring campaigns, especially B0712 and B1030.