Lens Models of Herschel-Selected Galaxies From High-Resolution Near-IR Observations

TL;DR

This study uses high-resolution near-infrared imaging to model gravitational lensing in Herschel-selected galaxies, revealing insights into their structure, magnification effects, and the relationship between stellar and dust components.

Contribution

It provides the first near-IR lens models for Herschel-selected galaxies, analyzing differential lensing and comparing properties with unlensed SMGs.

Findings

Approximately 17% of candidates show clear lensing morphologies.

Magnification factors for dust are about 1.5 times higher than for stellar emission.

Stellar emission is roughly twice as extended as dust emission.

Abstract

We present Keck-Adaptive Optics and Hubble Space Telescope high resolution near-infrared (IR) imaging for 500 um-bright candidate lensing systems identified by the Herschel Multi-tiered Extra-galactic Survey (HerMES) and Herschel Astrophysical Terahertz Survey (H-ATLAS). Out of 87 candidates with near-IR imaging, 15 (~17%) display clear near-IR lensing morphologies. We present near-IR lens models to reconstruct and recover basic rest-frame optical morphological properties of the background galaxies from 12 new systems. Sources with the largest near-IR magnification factors also tend to be the most compact, consistent with the size bias predicted from simulations and pre- vious lensing models for sub-millimeter galaxies. For four new sources that also have high-resolution sub-mm maps, we test for differential lensing between the stellar and dust components and find that the 880 um magnification factor (u_880) is ~1.5 times higher than the near-IR magnification factor (u_NIR), on average. We also find that the stellar emission is ~2 times more extended in size than dust. The rest-frame optical properties of our sample of Herschel-selected lensed SMGs are consistent with those of unlensed SMGs, which suggests that the two populations are similar.