DESI-253.2534+26.8843: A New Einstein Cross Spectroscopically Confirmed with VLT/MUSE and Modeled with GIGA-Lens

TL;DR

This paper confirms a rare Einstein Cross gravitational lens system using VLT/MUSE spectroscopy and models it with GIGA-Lens, providing detailed insights into the mass and structure of the lensing galaxy.

Contribution

It presents the first spectroscopic confirmation and detailed modeling of the DESI-253.2534+26.8843 Einstein Cross lens system, demonstrating the effectiveness of integral field spectroscopy and advanced lens modeling.

Findings

Confirmed the lensing nature with spectroscopic data

Determined the main lens's redshift and Einstein radius

Characterized the background source as a starburst galaxy

Abstract

Gravitational lensing provides unique insights into astrophysics and cosmology, including the determination of galaxy mass profiles and constraining cosmological parameters. We present spectroscopic confirmation and lens modeling of the strong lensing system DESI-253.2534+26.8843, discovered in the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys data. This system consists of a massive elliptical galaxy surrounded by four blue images forming an Einstein Cross pattern. We obtained spectroscopic observations of this system using the Multi Unit Spectroscopic Explorer (MUSE) on ESO's Very Large Telescope (VLT) and confirmed its lensing nature. The main lens, which is the elliptical galaxy, has a redshift of $z_{L1} = 0.636\pm 0.001$, while the spectra of the background source images are typical of a starburst galaxy and have a redshift of $z_s = 2.597 \pm 0.001$. Additionally, we identified a faint galaxy foreground of one of the lensed images, with a redshift of $z_{L2} = 0.386$. We employed the GIGA-Lens modeling code to characterize this system and determined the Einstein radius of the main lens to be $\theta_{E} =2.520{''}_{-0.031}^{+0.032}$, which corresponds to a velocity dispersion of $\sigma$ = 379 $\pm$ 2 km s$^{-1}$. Our study contributes to a growing catalog of this rare kind of strong lensing systems and demonstrates the effectiveness of spectroscopic integral field unit observations and advanced modeling techniques in understanding the properties of these systems.