Description
CLASS B2045+265 is a gravitationally lensed system where a radio-loud background galaxy is lensed by a radio-loud foreground galaxy, producing four lensed images. The flux-ratios of the four lensed images are known from previous observations to be inconsistent with the predictions from a simple singular isothermal ellipsoidal (SIE) model for the foreground mass distribution. This may suggest the presence of unresolved substructure or variability within the system.
As part of the Lensing over Frequency and Time (LoFT) project, we conducted broadband interferometric observations of CLASS B2045+265 using the VLA at 12–18 GHz over a 63-day monitoring period. With this high-resolution data set we have conducted a detailed investigation of the variability over time and frequency of the system, allowing us to explore the potential role of the dark matter substructure in producing the observed flux-ratio anomalies.
Our analysis demonstrates that such wide-band observations can probe the physical properties of lensing systems with a level of detail comparable to what SKA-MID will achieve in Band 5. By showcasing the capabilities of current instruments, this work highlights the potential of SKA-MID to extend these studies with higher sensitivity, faster processing, and superior RFI mitigation. Future SKA-MID observations will enable more robust tests of flux-ratio anomalies, ruling out variability-related effects, and offering unprecedented insights into the small-scale structure of dark matter in lensing systems.
