Strong gravitational lensing with upcoming wide-field radio surveys

Abstract

The number of strong lensing systems will soon increase by orders of magnitude thanks to sensitive, wide-field optical and infrared imaging surveys such as Euclid, Rubin-LSST, and Roman. A dramatic increase in strong lenses will also occur at radio wavelengths. The 2000-antenna Deep Synoptic Array (DSA-2000) will detect ~10⁹ continuum sources in the Northern hemisphere with a high mean redshift [〈z_s〉≈2 ], the Square Kilometre Array mid frequency telescope (SKA-Mid) will observe a large sample of extragalactic sources in the South with sub-arcsecond resolution, and the Very Large Array Sky Survey (VLASS) has recently completed. We forecast lensing rates for these telescopes, finding that each of the DSA-2000 and SKA-Mid will conservatively discover O(10⁴) strongly lensed systems, and optimistically as many as O(10⁵)⁠, a significant fraction of which will be galaxy group and cluster lenses. We propose strategies for strong lensing discovery in the limit where the Einstein radii are comparable to the point spread function (PSF) angular scale, taking advantage of modern computer vision techniques and multisurvey data. Finally, we describe applications of the expected radio strong lensing systems, including time-delay cosmography with transient and variable sources. We find that ~30–300 time-variable flat-spectrum active galactic nucleus (AGN) discovered by the DSA-2000 and SKA-Mid could be used to constrain H₀ at the per cent level with the appropriate follow-up.

Files

Additional details