J/A+A/706/A35 Ultra-diffuse galaxies from DES DR2 (Su+, 2026)
Searching for ultra-diffuse galaxies in the Dark Energy Survey using an object
detection algorithm.
Su Y., Yi Z., Li S., Liu M., Kong X., Bu Y., Li D.
<Astron. Astrophys. 706, A35 (2026)>
=2026A&A...706A..35S 2026A&A...706A..35S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Optical
Keywords: methods: data analysis - galaxies: abundances -
galaxies: star clusters: general
Abstract:
Ultra-diffuse galaxies (UDGs) are a class of galaxies characterized by
extremely low surface brightness and large effective radius.
The significance of UDGs lies in their unique properties, such as
their diverse dark matter content, which challenge existing theories
of galaxy formation and evolution. However, their low surface
brightness and diffuse stellar distributions make UDGs particularly
difficult to detect. To address this challenge, this study introduces
UDGnet-DES, a deep learning-based object detection model, combined
with an iterative training strategy, to conduct a large-scale search
for UDG candidates in the Dark Energy Survey (DES) DR2 imaging data.
Using our model, we searched UDGs from more than 500000 DES images
and further filtered the results based on surface brightness and
visual inspection. As a result, we obtained a catalog of 2991 UDG
samples, of which 39 have spectroscopic redshifts.
Analysis of our UDG samples reveals that most objects exhibit nearly
circular morphologies. Among them, blue UDGs tend to have higher
surface brightness, while red UDGs show significant spatial
clustering, in contrast to the more uniformly distributed blue
UDGs.The method developed in this study can improve the efficiency of
UDG searches and will be applied to the search for UDGs in the China
Space Station Telescope (CSST) survey project.
Description:
The Dark Energy Survey (DES) is a six-year large-scale optical and
near-infrared imaging survey covering approximately 5000 deg2 of the
southern sky. we used data from the Dark Energy Survey Data Release 2
(DES DR2) covering the sky region with declination >-30°.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablee1.dat 73 39 Catalog of UDGs with spectroscopic redshifts
detected in DES DR2
tablee2.dat 66 2952 Catalog of candidate UDGs detected in DES DR2
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See also:
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
Byte-by-byte Description of file: tablee1.dat
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Bytes Format Units Label Explanations
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1- 10 I10 --- CoadID DES DR2 unique identifier
12- 24 F13.9 deg RAdeg Right ascension (J2000)
26- 38 F13.9 deg DEdeg Declination (J2000)
40- 44 F5.2 mag gmag g-band magnitude
46- 49 F4.2 --- q Axis ratio
51- 54 F4.2 mag g-i g-i color
56- 60 F5.2 mag/arcsec2 SuBrg Mean effective surface brightness in g-band
62- 67 F6.4 --- z redshift
69- 73 F5.2 kpc Re Physical effective radius
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Byte-by-byte Description of file: tablee2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- CoadID DES DR2 unique identifier
12- 24 F13.9 deg RAdeg Right ascension (J2000)
26- 38 F13.9 deg DEdeg Declination (J2000)
40- 44 F5.2 mag gmag g-band magnitude
46- 49 F4.2 --- q Axis ratio
51- 54 F4.2 mag g-i g-i color
56- 60 F5.2 mag/arcsec2 SuBrg Mean effective surface brightness in g-band
62- 66 F5.2 arcsec re Effective radius
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Acknowledgements:
Yiping Su, syp20001013(at)163.com
(End) Patricia Vannier [CDS] 10-Nov-2025