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Abstract We present a mock catalog of gravitationally-lensed quasars atzqso< 7.5 with simulated images for the Rubin Observatory Legacy Survey of Space and Time (LSST). We adopt recent measurements of quasar-luminosity functions to model the quasar population, and use the CosmoDC2 mock galaxy catalog to model the deflector galaxies, which successfully reproduces the observed galaxy-velocity dispersion functions up tozd∼ 1.5. The mock catalog is highly complete for lensed quasars with Einstein radiusθE> 0.″07 and quasar absolute magnitudeMi< − 20. We estimate that there are ∼103lensed quasars discoverable in current imaging surveys, and LSST will increase this number to ∼ 2.4 × 103. Most of the lensed quasars have image separation Δθ> 0.″5, which will at least be marginally resolved in LSST images with seeing of ∼0.″7. There will be ∼200 quadruply-lensed quasars discoverable in the LSST. The fraction of quad lenses among all discoverable lensed quasars is about ∼10%–15%, and this fraction decreases with survey depth. This mock catalog shows a large diversity in the observational features of lensed quasars, in terms of lensing separation and quasar-to-deflector flux ratio. We discuss possible strategies for a complete search of lensed quasars in the LSST era.
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Revisiting the Lensed Fraction of High-redshift Quasars
Abstract The observed lensed fraction of high-redshift quasars (∼0.2%) is significantly lower than previous theoretical predictions (≳4%). We revisit the lensed fraction of high-redshift quasars predicted by theoretical models, where we adopt recent measurements of galaxy velocity dispersion functions (VDFs) and explore a wide range of quasar luminosity function (QLF) parameters. We use both analytical methods and mock catalogs, which give consistent results. For ordinary QLF parameters and the depth of current high-redshift quasar surveys (mz≲ 22), our model suggests a multiply imaged fraction ofFmulti∼ 0.4%–0.8%. The predicted lensed fraction is ∼1%–6% for the brightestzs∼ 6 quasars (mz≲ 19), depending on the QLF. The systematic uncertainties of the predicted lensed fraction in previous models can be as large as 2–4 times and are dominated by the VDF. Applying VDFs from recent measurements decreases the predicted lensed fraction and relieves the tension between observations and theoretical models. Given the depth of current imaging surveys, there are ∼15 lensed quasars atzs> 5.5 detectable over the sky. Upcoming sky surveys like the Legacy Survey of Space and Time survey and the Euclid survey will find several tens of lensed quasars at this redshift range.
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- Award ID(s):
- 1908284
- PAR ID:
- 10362260
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 925
- Issue:
- 2
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 169
- Size(s):
- Article No. 169
- Sponsoring Org:
- National Science Foundation
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