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Discovery of two bright high-redshift gravitationally lensed quasars revealed by Gaia.
- Source :
- Monthly Notices of the Royal Astronomical Society; Jan2022, Vol. 509 Issue 1, p738-747, 10p
- Publication Year :
- 2022
-
Abstract
- We present the discovery and preliminary characterisation of two high-redshift gravitationally lensed quasar systems in Gaia Data Release 2 (DR2). Candidates with multiple close-separation Gaia detections and quasar-like colours in WISE , Pan-STARRS, and DES are selected for follow-up spectroscopy with the New Technology Telescope. We confirm DES J215028.71−465251.3 as a |$z$| = 4.130 ± 0.006 asymmetric, doubly imaged lensed quasar system and model the lensing mass distribution as a singular isothermal sphere. The system has an Einstein radius of 1.202 ± 0.005 arcsec and a predicted time delay of ∼122.0 d between the quasar images, assuming a lensing galaxy redshift of |$z$| = 0.5, making this a priority system for future optical monitoring. We confirm PS J042913.17+142840.9 as a |$z$| = 3.866 ± 0.003 four-image quasar system in a cusp configuration, lensed by two foreground galaxies. The system is well modelled using a singular isothermal ellipsoid for the primary lens and a singular isothermal sphere for the secondary lens with Einstein radii 0.704 ± 0.006 and 0.241 ± 0.030 arcsec, respectively. A maximum predicted time delay of 9.6 d is calculated, assuming lensing galaxy redshifts of |$z$| = 1.0. Furthermore, PS J042913.17+142840.9 exhibits a large flux ratio anomaly, up to a factor of 2.66 ± 0.37 in i band, that varies across optical and near-infrared wavelengths. We discuss LSST and its implications for future high-redshift lens searches and outline an extension to the search using supervised machine learning techniques. [ABSTRACT FROM AUTHOR]
- Subjects :
- QUASARS
SUPERVISED learning
GALACTIC redshift
DATA release
Subjects
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 509
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 154542518
- Full Text :
- https://doi.org/10.1093/mnras/stab2960