J/ApJS/280/69 Dust-lane spheroidal galaxies from DESI-LS (Luo+, 2025)
Identifying dust-lane spheroidal galaxies in DESI Legacy Imaging Surveys using
semisupervised methods.
Luo Z., Chen J., Pei W., Xiao H., Zhang S., Cui Q., Shu C.
<Astrophys. J. Suppl. Ser., 280, 69 (2025)>
=2025ApJS..280...69L 2025ApJS..280...69L
ADC_Keywords: Galaxy catalogs; Morphology; Photometry; Optical; Redshifts;
Surveys
Keywords: Galaxies ; Astronomy data analysis ; Astronomy image processing ;
Convolutional neural networks ; Ground-based astronomy ;
Computational astronomy
Abstract:
Dust-lane spheroidal galaxies (DLSGs) are unique astrophysical systems
that exhibit the morphology of early-type galaxies (ETGs) but are
distinguished by prominent dust lanes. Recent studies propose that
they form through minor mergers between ETGs and gas-rich dwarf
galaxies, offering a window into the interstellar medium (ISM) of ETGs
and star formation triggered by small-scale interactions. However,
their rarity poses a challenge for assembling large, statistically
robust samples via manual selection. To overcome this limitation, we
employ GC-SWGAN, a semisupervised learning method developed by
Luo+ 2025ApJS..279...17L 2025ApJS..279...17L, to systematically identify DLSGs within the
DESI Legacy Imaging Surveys (DESI-LS). The methodology involves
training a generative adversarial network on unlabeled galaxy images
to extract morphological features, followed by fine-tuning the model
using a small data set of labeled DLSGs. In our experiments, despite
DLSGs constituting only ∼3.7% of the test set, GC-SWGAN achieves
remarkable performance, with an 87% recall rate, 84% accuracy, and an
F1 score of 86%, underscoring its efficacy for DLSG detection. By
applying this model to ∼310,000 DESI-LS galaxies that meet the
criteria mr<17.0 and 0.01<z<0.07 we compile the largest catalog of
DLSG candidates to date, identifying 9482 dust-lane ETGs. A
preliminary analysis reveals that these DLSGs exhibit significantly
redder g-r colors and higher specific star formation rates compared to
non-DLSGs. This catalog enables future studies of ISM properties in
ETGs and the role of minor mergers in driving star formation in the
nearby Universe.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 70 9482 Catalog of 9,482 model-identified dust-lane
spheroidal galaxy (DLSG) candidates
from the DESI Legacy Imaging Surveys (DESI-LS)
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See also:
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
VII/292 : DESI Legacy Imaging Surveys DR8 photometric redshifts (Duncan, 2022)
V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025)
J/A+A/519/A40 : Spectroscopic study of 65 nearby galaxies (Annibali+, 2010)
J/MNRAS/414/940 : ATLAS3D project. IV. (Young+, 2011)
J/MNRAS/435/2835 : Morphological types from Galaxy Zoo 2 (Willett+, 2013)
J/ApJS/219/1 : Catalog of Type-1 AGNs from SDSS-DR7 (Oh+, 2015)
J/AJ/154/86 : MaNGA catalog, DR15 (Wake+, 2017)
J/ApJ/864/123 : Morphological param. of galaxies with GALEX (Mager+, 2018)
J/MNRAS/491/2280 : Neural networks for spectral classification (Sharma+, 2020)
J/MNRAS/526/4768 : Galaxy Zoo DESI (Walmsley+, 2023)
http://d.legacysurvey.org/ : DESI Legacy Surveys home page
http://www.sdss4.org/dr17/manga/manga-target-selection/nsa/ : NASA-Sloan Atlas
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- DESI DESI-LS DR8 unique identifier (brickid_objid)
13- 22 F10.6 deg RAdeg Right Ascension (J2000)
24- 33 F10.6 deg DEdeg [-65.3/84.3] Declination (J2000)
35- 40 F6.3 mag rmag [10.8/17] DESI apparent r band magnitude
42- 47 F6.3 mag imag [11.7/18.3]? DESI apparent i band magnitude (1)
49- 54 F6.3 mag zmag [10/18] DESI apparent z band magnitude
56- 61 F6.4 --- z [0.01/0.07] Galaxy redshift (2)
63- 70 F8.6 --- Prob [0.5/1] Probability that each galaxy is predicted
as a DLSG by the model
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Note (1): A blank indicates a Infinite value.
Note (2): Prioritization order:
1. SDSS spectroscopic redshift from the NASA-Sloan Atlas (NSA;
Aguado+ 2019ApJS..240...23A 2019ApJS..240...23A)
2. OSSY (Oh+ 2015, J/ApJS/219/1) spectroscopic redshift;
3. Zhou+ 2021MNRAS.501.3309Z 2021MNRAS.501.3309Z spec-z/photo-z columns.
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Jun-2026