A Redshift for the First Einstein Ring, MG 1131+0456

Abstract

MG 1131+0456 is a radio-selected gravitational lens, and is the first known Einstein ring. Discovered in 1988, the system consists of a bright radio source imaged into a ring and two compact, flat-spectrum components separated by 2.1 arcsec. The ring is optically faint (R = 23.3), rising steeply into the near- and mid-infrared (K = 17.8; W2 = 13.4). The system has been intensively studied in the intervening years, including high-resolution radio imaging, radio monitoring, and near-infrared imaging with Hubble and Keck. The lensing galaxy is at z(lens) = 0.844. However, to date, no spectroscopic redshift had been reported for the lensed source. Using archival Keck data from 1997, we report the robust detection of a single narrow emission line at 5438 Angstroms, which we associate with CIII] 1909 from a type-2 quasar at z(source) = 1.849. Support for this redshift identification comes from weaker emission associated with CIV 1549 and HeII 1640, typical of type-2 quasars, as well as the lack of emission lines in archival near-infrared Keck spectroscopy. We also present, for the first time, Cycle 1 Chandra observations of MG 1131+0456, which clearly resolves into two point sources with a combined flux of ~1e-13 erg/cm2/s and a best-fit column density of ~3e22 /cm2. We suggest a new method to identify candidate lensed active galactic nuclei from low-resolution X-ray surveys such as eROSITA by targeting sources that have anomalously high X-ray luminosity given their mid-infrared luminosity.

5 pages, 3 figures; published in ApJ Letters

References in corpus (28)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• On the Absorption of X-rays in the Interstellar Medium
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Mid-Infrared Selection of AGN with the Wide-Field Infrared Survey Explorer. I. Characterizing WISE-Selected AGN in COSMOS
• An Overview of the Performance and Scientific Results from the Chandra X-Ray Observatory (CXO)
• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• Dynamical family properties and dark halo scaling relations of giant elliptical galaxies
• The VLA Low-frequency Sky Survey
• Mid-Infrared Selection of Active Galactic Nuclei with the Wide-Field Infrared Survey Explorer. II. Properties of WISE-Selected Active Galactic Nuclei in the NDWFS Boötes Field
• The X-ray Properties of the Most-Luminous Quasars from the Sloan Digital Sky Survey
• ESI, a new Keck Observatory echellette spectrograph and imager
• Resolving the mid-infrared cores of local Seyferts
• A statistical relation between the X-ray spectral index and Eddington ratio of active galactic nuclei in deep surveys
• Mass-to-Light Ratios of Field Early-Type Galaxies at z~1 from Ultra-Deep Spectroscopy: Evidence for Mass-dependent Evolution
• The Fundamental Plane of Gravitational Lens Galaxies and The Evolution of Early-Type Galaxies in Low Density Environments
• The FIRST-2MASS Red Quasar Survey
• Chandra Detection of a TypeII Quasar at z=3.288
• The X-Ray to Mid-Infrared Relation of AGN at High Luminosity
• Chandra/ACIS Subpixel Event Repositioning. II. Further Refinements and Comparison between Backside and Front-side Illuminated X-ray CCDs
• The mid IR -- hard X-ray correlation in AGN and its implications for dusty torus models
• Cosmic Chronometers: Constraining the Equation of State of Dark Energy. II. A Spectroscopic Catalog of Red Galaxies in Galaxy Clusters
• PMN J0134-0931: A gravitationally lensed quasar with an unusual radio morphology
• Redshifts of the Gravitational Lenses MG1131+0456 and B1938+666
• New High-Redshift Radio Galaxies from the MIT-Green Bank Catalog
• A Rapidly Spinning Black Hole Powers the Einstein Cross
• The Mass Distribution of the Lens Galaxy in MG1131+0456
• Three QSOs acting as strong gravitational lenses
• A highly magnified gravitationally lensed red quasar at z = 2.5 with significant flux anomaly: Uncovering a missing population

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