# Lens Model and Source Reconstruction Reveal the Morphology and Star Formation Distribution in the Cool Spiral LIRG SGAS J143845.1$+$145407

## TL;DR

This study uses HST imaging and lens modeling to analyze the distribution of star formation in a strongly lensed LIRG at z=0.816, revealing widespread star formation with a central deficit likely caused by dust extinction.

## Contribution

It provides a detailed lens model and source reconstruction of a z=0.816 LIRG, offering new insights into its star formation distribution and dust effects.

## Key findings

- Magnification ranges from 2 to 10, total magnification is 11.8.
- Star formation is widespread across the galaxy.
- Central Hα deficit suggests dust extinction effects.

## Abstract

We present $Hubble\ Space\ Telescope$ ($HST$) imaging and grism spectroscopy of a strongly lensed LIRG at $z=0.816$, SGAS 143845.1$+$145407, and use the magnification boost of gravitational lensing to study the distribution of star formation throughout this galaxy. Based on the $HST$ imaging data, we create a lens model for this system; we compute the mass distribution and magnification map of the $z=0.237$ foreground lens. We find that the magnification of the lensed galaxy ranges between $2$ and $10$, with a total magnification (measured over all the images of the source) of $\mu=11.8^{+4.6}_{-2.4}$. We find that the total projected mass density within $\sim34$ kpc of the brightest cluster galaxy is $6.0^{+0.3}_{-0.7}\times10^{12}\,M_{\odot}$. Using the lens model we create a source reconstruction for SGAS 143845.1$+$145407, which paired with a faint detection of H$\alpha$ in the grism spectroscopy, allows us to finally comment directly on the distribution of star formation in a $z\sim1$ LIRG. We find widespread star formation across this galaxy, in agreement with the current understanding of these objects. However, we note a deficit of H$\alpha$ emission in the nucleus of SGAS 143845.1$+$145407, likely due to dust extinction.