J/ApJS/269/61 Multiply lensend quasar systems in the DESI Surveys (Dawes+, 2023)
Finding multiply lensed and binary quasars in the DESI Legacy Imaging Surveys.
Dawes C., Storfer C., Huang X., Aldering G., Cikota A., Dey A.,
Schlegel D.J.
<Astrophys. J. Suppl. Ser., 269, 61 (2023)>
=2023ApJS..269...61D 2023ApJS..269...61D
ADC_Keywords: Gravitational lensing; QSOs; Redshifts; Spectra, optical;
Photometry, ugriz; Surveys
Keywords: Quasars ; Double quasars ; Gravitational lensing ;
Strong gravitational lensing ; Hubble constant ; Galaxy evolution
Abstract:
The time delay between multiple images of strongly lensed quasars is a
powerful tool for measuring the Hubble constant (H0). To achieve H0
measurements with higher precision and accuracy using the time delay,
it is crucial to expand the sample of lensed quasars. We conduct a
search for strongly lensed quasars in the Dark Energy Spectroscopic
Instrument (DESI) Legacy Imaging Surveys. The DESI Legacy Surveys
comprise 19000deg2 of the extragalactic sky observed in three
optical bands (g, r, and z), making it well suited for the discovery
of new strongly lensed quasars. We apply an autocorrelation algorithm
to ∼5 million objects classified as quasars in the DESI Quasar Sample.
These systems are visually inspected and ranked. Here, we present 436
new multiply lensed and binary quasar candidates, 65 of which have
redshifts from Sloan Digital Sky Survey Data Release 16. We provide
redshifts for an additional 18 candidates from the SuperNova Integral
Field Spectrograph.
Description:
We have observed a subset of our high-quality candidates with r-band
mag ≲20.0 on the SNIFS instrument on the University of Hawaii 88-inch
(2.2m) telescope (UH88), located on Maunakea. The spectrograph has two
channels, blue (320nm to 560nm) and red (520nm to 1um), with
resolutions of R∼1000 and R∼1300, respectively. Our candidates were
observed on the nights of 2020 September 21, October 12, October 19,
and Nov-09 as well as 2021 June 11, June 14, July 12, and Nov-08 UTC.
See Section 4.2.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 89 875 New candidates
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See also:
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)
VII/292 : DESI Legacy Imaging Surveys DR8 photometric redshifts (Duncan, 2022)
J/AJ/143/119 : SDSS Quasar Lens Search. V. Final catalog (Inada+, 2012)
J/A+A/622/A165 : Gaia GraL. III. New lensed systems (Delchambre+, 2019)
J/ApJ/876/85 : HST observations for LMC Cepheids (Riess+, 2019)
J/MNRAS/486/4987 : Gravitationally lensed quasars in Pan-STARRS1 (Rusu+, 2019)
J/ApJ/894/78 : Strong gravitational lenses from DECaLS (Huang+, 2020)
J/A+A/642/A148 : SuGOHI VI. List up to 2020 (Sonnenfeld+, 2020)
J/ApJ/909/27 : Gravitational lenses in DESI Legacy Surveys (Huang+, 2021)
J/ApJ/921/42 : Gaia GraL. VI. Quadruply imaged lensed QSOs (Stern+, 2021)
J/A+A/672/A123 : Lensed QSO candidates in DESI-LS DR9 (He+, 2023)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Index [1/436] Index number
5- 25 A21 --- Name System name; RA & DE in decimal format
27 A1 --- Grade Human inspection grade ("A":highest confidence,
"B", "C" or NULL for nonlens; see Section 4)
29- 35 F7.5 --- zsp [0.36/3.6]? Quasar spectroscopic redshift from
SDSS DR16
36 A1 --- f_zsp [*] * = redshift from SNIFS instead of SDSS DR16
38- 42 F5.3 --- zph [0.1/2.5]? Photometric redshift of putative
lensing galaxy from Zhou+ (2021MNRAS.501.3309Z 2021MNRAS.501.3309Z)
44- 48 F5.3 --- e_zph [0.04/0.6]? Uncertainty in zph
51- 55 F5.2 mag gmag [17.6/24.3] Apparent g band AB magnitude
57- 61 F5.2 mag rmag [17.5/23] Apparent r band AB magnitude
63- 67 F5.2 mag zmag [17.2/22.6] Apparent z band AB magnitude
69- 72 F4.2 --- PXSig [0/3.4]? Parallax significance
74- 77 F4.2 --- PMSig [0.05/7.8]? Proper motion significance
79- 84 A6 --- Type Double or quad grouping
86- 89 F4.2 arcsec Sep [0.3/5]? Average separation of image
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Feb-2024