J/ApJ/954/68 Galaxy-galaxy strong lens cand. from DELVE (Zaborowski+, 2023)
Identification of galaxy-galaxy strong lens candidates in the DECam Local Volume
Exploration Survey using machine learning.
Zaborowski E.A., Drlica-Wagner A., Ashmead F., Wu J.F., Morgan R.,
Bom C.R., Shajib A.J., Birrer S., Cerny W., Buckley-Geer E.J.,
Mutlu-Pakdil B., Ferguson P.S., Glazebrook K., Lozano S.J.G., Gordon Y.,
Martinez M., Manwadkar V., O'Donnell J., Poh J., Riley A., Sakowska J.D.,
Santana-Silva L., Santiago B.X., Sluse D., Tan C.Y., Tollerud E.J.,
Verma A., Carballo-Bello J.A., Choi Y., James D.J., Kuropatkin N.,
Martinez-Vazquez C.E., Nidever D.L., Castellon J.L.N., Noel N.E.D.,
Olsen K.A.G., Pace A.B., Mau S., Yanny B., Zenteno A., Abbott T.M.C.,
Aguena M., Alves O., Andrade-Oliveira F., Bocquet S., Brooks D.,
Burke D.L., Carnero Rosell A., Carrasco Kind M., Carretero J.,
Castander F.J., Conselice C.J., Costanzi M., Pereira M.E.S.,
De Vicente J., Desai S., Dietrich J.P., Doel P., Everett S., Ferrero I.,
Flaugher B., Friedel D., Frieman J., Garcia-Bellido J., Gruen D.,
Gruendl R.A., Gutierrez G., Hinton S.R., Hollowood D.L., Honscheid K.,
Kuehn K., Lin H., Marshall J.L., Melchior P., Mena-Fernandez J.,
Menanteau F., Miquel R., Palmese A., Paz-Chinchon F., Pieres A.,
Malagon A.A.P., Prat J., Rodriguez-Monroy M., Romer A.K., Sanchez E.,
Scarpine V., Sevilla-Noarbe I., Smith M., Suchyta E., To C.,
Weaverdyck N., DELVE & DES Collaborations
<Astrophys. J., 954, 68 (2023)>
=2023ApJ...954...68Z 2023ApJ...954...68Z
ADC_Keywords: Gravitational lensing; Photometry, ugriz; Surveys
Keywords: Strong gravitational lensing
Abstract:
We perform a search for galaxy-galaxy strong lens systems using a
convolutional neural network (CNN) applied to imaging data from the
first public data release of the DECam Local Volume Exploration
Survey, which contains ∼520 million astronomical sources covering
∼4000deg2 of the southern sky to a 5σ point-source depth of
g=24.3, r=23.9, i=23.3, and z=22.8mag. Following the methodology of
similar searches using Dark Energy Camera data, we apply color and
magnitude cuts to select a catalog of ∼11 million extended
astronomical sources. After scoring with our CNN, the highest-scoring
50000 images were visually inspected and assigned a score on a scale
from 0 (not a lens) to 3 (very probable lens). We present a list of
581 strong lens candidates, 562 of which are previously unreported. We
categorize our candidates using their human-assigned scores, resulting
in 55 Grade A candidates, 149 Grade B candidates, and 377 Grade C
candidates. We additionally highlight eight potential quadruply lensed
quasars from this sample. Due to the location of our search footprint
in the northern Galactic cap (b>10deg) and southern celestial
hemisphere (decl.<0deg), our candidate list has little overlap with
other existing ground-based searches. Where our search footprint does
overlap with other searches, we find a significant number of
high-quality candidates that were previously unidentified, indicating
a degree of orthogonality in our methodology. We report properties of
our candidates including apparent magnitude and Einstein radius
estimated from the image separation.
Description:
The DECam Local Volume Exploration Survey (DELVE) data were assembled
from multiband imaging by DECam on the 4m Blanco Telescope at Cerro
Tololo Inter-American Observatory in Chile.
The first DELVE data release (DELVE DR1;
Drlica-Wagner+ 2021ApJS..256....2D 2021ApJS..256....2D) provides a catalog of ∼520 million
unique astronomical sources assembled from ∼5000deg2 of the
high-Galactic-latitude sky in the northern Galactic cap (b>10 and
decl.<0). This region is distinct from the DES footprint and overlaps
with DECaLS only in the region with decl.>-7 (Figure 1).
Our search yields a catalog of 581 candidate strong lens systems. Using
the criteria outlined in Section 3.4, we identify 55 Grade A
candidates, 149 Grade B candidates, and 377 Grade C candidates.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 121 1691 Locations and properties of our candidate
lens systems
--------------------------------------------------------------------------------
See also:
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
J/ApJ/682/964 : Sloan lens ACS survey. V. (Bolton+, 2008)
J/ApJ/690/1236 : COSMOS photometric redshift catalog (Ilbert+, 2009)
J/ApJ/749/38 : CFHTLS-SL2S-ARCS strong lens candidates (More+, 2012)
J/A+A/556/A22 : R-band light curves of RX J1131-1231 (Tewes+, 2013)
J/ApJ/785/144 : SL2S galaxy-scale sample of lens candidates (Gavazzi+, 2014)
J/MNRAS/465/4914 : R-band light curves of HE 0435-1223 (Bonvin+, 2017)
J/ApJS/232/15 : Candidate strong lens systems from DES obs. (Diehl+, 2017)
J/ApJ/851/48 : SLACS. XIII. Galaxy-scale strong lens cand. (Shu+, 2017)
J/ApJ/864/91 : Compilation of galaxy-galaxy strong-lens syst. (Shu+, 2018)
J/A+A/622/A165 : Gaia GraL. III. New lensed systems (Delchambre+, 2019)
J/ApJS/243/17 : Strong DES lens cand. from neural networks (Jacobs+, 2019)
J/MNRAS/484/5330 : High-z strong lens candidates from DES (Jacobs+, 2019)
J/MNRAS/484/3879 : Galaxy-scale lenses in the KiDS (Petrillo+, 2019)
J/ApJ/876/85 : HST observations for LMC Cepheids (Riess+, 2019)
J/A+A/644/A163 : Pan-STARRS lens cand. from neural networks (Canameras+ 2020)
J/ApJ/894/78 : Strong gravitational lenses from DECaLS (Huang+, 2020)
J/MNRAS/495/1291 : SuGOHI. V. Group-to-cluster scale lenses (Jaelani+, 2020)
J/A+A/642/A148 : SuGOHI VI. List up to 2020 (Sonnenfeld+, 2020)
J/A+A/653/L6 : HSC-SSP lens cand. from neural networks (Canameras+, 2021)
J/ApJ/916/50 : HST/WFC3 sp. of 2 strongly lensed gal. (Florian+, 2021)
J/ApJ/909/27 : Strong gravitational lenses in DESI Surveys (Huang+, 2021)
J/ApJ/921/42 : Gaia GraL. VI. Quadruply imaged lensed QSOs (Stern+, 2021)
J/A+A/667/A141 : Hubble Asteroid Hunter. II. (Garvin+, 2022)
J/ApJS/259/27 : DES Bright Arcs Survey: strong lens syst. (O'Donnell+, 2022)
J/A+A/668/A73 : Search of strong lens systems in DES (Rojas+, 2022)
J/A+A/662/A4 : Strong-lens candidates from HSC-SSP PDR2 (Shu+, 2022)
J/PASJ/74/1209 : SuGOHI VIII. Lens candidates (Wong+, 2022)
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- ID Lens candidate identifier
23- 26 F4.2 --- Rating [0.3/2.6] Mean final rating
28 A1 --- Grade Grade (A=high-confidence candidate) (1)
30- 35 A6 --- Type Object type; Lens or source (2)
37- 40 F4.2 arcsec rE [0.86/9.9]? Estimated Einstein radius
42- 45 F4.2 arcsec e_rE [0.26/1.7]? Uncertainty in rE
47- 62 A16 --- DELVE DELVE DR1 lens galaxy object identifier
64- 79 A16 --- ObjID DELVE DR1 object identifier
81- 88 F8.4 deg RAdeg [117.48/244.1] Right Ascension (J2000)
90- 97 F8.4 deg DEdeg [-48.4/0.4] Declination (J2000)
99- 103 F5.2 mag gmag [16.9/24.1]? Apparent CTIO/DECam g-band AB
magnitude
105- 109 F5.2 mag rmag [16.56/23.8]? Apparent CTIO/DECam r-band AB
magnitude
111- 115 F5.2 mag imag [16.28/23.2]? Apparent CTIO/DECam i-band AB
magnitude
117- 121 F5.2 mag zmag [16/23]? Apparent CTIO/DECam z-band AB
magnitude
--------------------------------------------------------------------------------
Note (1): This table contains 581 candidate strong lens systems (Grades A, B,
and C) and 36 such systems which were later flagged as likely
nonlenses (Grade F).
Note (2): For each candidate system, there are multiple records, one for each
associated lens galaxy (Type = "lens") or source galaxy
(Type = "source"). The table thus contains a total of 1,691 records.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS), Emmanuelle Perret [CDS] 01-Oct-2025