The Canarias Einstein Ring: a Newly Discovered Optical Einstein Ring

TL;DR

This paper reports the serendipitous discovery of a nearly complete optical Einstein Ring in the Sculptor constellation, confirmed through spectroscopic redshifts, and estimates the lensing galaxy's mass to be approximately 1.86 trillion solar masses.

Contribution

It presents the first discovery and spectroscopic confirmation of an optical Einstein Ring near the Sculptor Dwarf Galaxy, including mass estimation of the lensing galaxy.

Findings

Discovery of a nearly complete Einstein Ring with 300° coverage.

Spectroscopic redshifts confirm the lens at z=0.581 and source at z=1.165.

Estimated total mass of the lensing galaxy is (1.86 ± 0.23) × 10^12 solar masses.

Abstract

We report the discovery of an optical Einstein Ring in the Sculptor constellation, IAC J010127-334319, in the vicinity of the Sculptor Dwarf Spheroidal Galaxy. It is an almost complete ring ($\sim 300^{\circ}$) with a diameter of $\sim 4.5\, {\rm arcsec}$. The discovery was made serendipitously from inspecting Dark Energy Camera (DECam) archive imaging data. Confirmation of the object nature has been obtained by deriving spectroscopic redshifts for both components, lens and source, from observations at the $10.4$ m Gran Telescopio CANARIAS (GTC) with the spectrograph OSIRIS. The lens, a massive early-type galaxy, has a redshift of ${\rm z}=0.581$ while the source is a starburst galaxy with redshift of ${\rm z}=1.165$. The total enclosed mass that produces the lensing effect has been estimated to be ${\rm M_{tot}=(1.86 \pm 0.23) \,\cdot 10^{12}\, {\rm M_{\odot}}}$.