Year: 2025
Type: article
Abstract: We report the discovery of the first example of an Einstein zigzag lens, an extremely rare lensing configuration. In this system, J1721+8842, six images of the same background quasar are formed by two intervening galaxies, one at redshift z1 = 0.184 and another at z2 = 1.885. Two out of the six multiple images are deflected in opposite directions as they pass the first lens galaxy on one side and the second on the other side – the optical paths forming zigzags between the two deflectors. In this paper we demonstrate that J1721+8842, previously thought to be a lensed dual quasar, is in fact a compound lens, with the more distant lens galaxy also being distorted as an arc by the foreground galaxy. Evidence supporting this unusual lensing scenario includes: (1) identical light curves in all six lensed quasar images obtained from two years of monitoring at the Nordic Optical Telescope; (2) detection of the additional deflector at redshift z2 = 1.885 in JWST/NIRSpec integral field unit data; and (3) a multiple-plane lens model reproducing the observed image positions. This unique configuration offers the opportunity to combine two major lensing cosmological probes, time-delay cosmography and dual source-plane lensing, since J1721+8842 features multiple lensed sources that form two distinct Einstein radii of different sizes, one of which is a variable quasar. We expect to place tight constraints on H0 and w by combining these two probes of the same system. The z2 = 1.885 deflector, a quiescent galaxy, is also the highest-redshift strong galaxy-scale lens with a spectroscopic redshift measurement known to date.
Institutions: European Southern Observatory, École Polytechnique Fédérale de Lausanne, ETH Zurich, Kavli Institute for Particle Astrophysics and Cosmology, Institute for Particle Physics and Astrophysics, Stanford University, Stockholm University, University of California, Los Angeles, Institució Catalana de Recerca i Estudis Avançats, Institut de Ciències del Cosmos, Universitat de Barcelona, University of Chicago, Stony Brook University, The University of Tokyo, University of Copenhagen, Sci-Tech Daresbury, Universidad Andrés Bello, Max Planck Institute for Astrophysics, Technical University of Munich, University of Milan, National Institute for Astrophysics, University of Liège
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, Villum Fonden, Space Telescope Science Institute, European Commission, Deutsche Forschungsgemeinschaft, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Max-Planck-Gesellschaft, HORIZON EUROPE Framework Programme, Japan Society for the Promotion of Science
Awards: G103270039, G1338664626, Probing the Cosmos with Strong Gravitational Lensing, G1700342535, G1897041155, Etude ethnoarchéologique de la céramique du Delta intérieur du Niger (Mali)., G256731684, Time-delay cosmography in the era of large sky sruvey, G3043396493, G3418879279, G380733860, G4066435496, EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens, Time-delay cosmography in the era of large sky surveys, G5568641063, G5771713820, Cosmology with wide-field surveys and a fast emulator, G685589434
OpenAlex ID: W7127110429
FWCI:
Cites:
Cited by:
Related to: