Line-of-sight shear in SLACS strong lenses II: validation tests with an extended sample
Strong gravitational lensing images are subject to shape distortions due to inhomogeneities along the line of sight. The leading order shape distortion is shear, which, if measurable, will be a complementary cosmological probe to traditional cosmic shear. In Hogg et al. (2025a), we modelled 23 of the SLACS strong lenses, studying the line-of-sight (LOS) shear under a variety of shear and mass model parametrisations. In this work, we successfully model 22 of an additional 27 lenses, extending our sample of LOS shear constraints to 45 in total. We find a mean shear magnitude of $0.11\pm 0.024$, showing that a significant fraction of the lenses modelled in this work possess LOS shears with unexpectedly large magnitudes, $|\gamma_{\rm LOS}| > 0.1$, even when an octupolar distortion is included in the lens mass. We further investigate if factors such as lens and source redshift, filter and PSF, or flux and signal-to-noise ratio in the lensed arcs correlate with shear. We find that none of these features play a statistically significant role in the production of unusually large shear magnitudes.