Line-of-sight shear in SLACS strong lenses II: validation tests with an extended sample

Fuente: arXiv
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Main Authors: Hogg, Natalie B., Johnson, Daniel, Shajib, Anowar J., Larena, Julien
Format: Preprint
Published: 2025
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author Hogg, Natalie B.
Johnson, Daniel
Shajib, Anowar J.
Larena, Julien
author_facet Hogg, Natalie B.
Johnson, Daniel
Shajib, Anowar J.
Larena, Julien
contents 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 model 27 additional 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, $|γ_{\rm LOS}| > 0.1$, 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.
format Preprint
id arxiv_https___arxiv_org_abs_2512_05050
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Line-of-sight shear in SLACS strong lenses II: validation tests with an extended sample
Hogg, Natalie B.
Johnson, Daniel
Shajib, Anowar J.
Larena, Julien
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
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 model 27 additional 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, $|γ_{\rm LOS}| > 0.1$, 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.
title Line-of-sight shear in SLACS strong lenses II: validation tests with an extended sample
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2512.05050