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ORIGINAL RESEARCH article
Front. Astron. Space Sci.
Sec. Extragalactic Astronomy
Volume 12 - 2025 | doi: 10.3389/fspas.2025.1560380
Searching for Nearby Diffuse Dwarf Galaxies in the COSMOS Field
Provisionally accepted
DongDong Shi 1*
XianZhong Zheng 2* Zhizheng Pan 3* Yu Luo 4* Hongxia Deng 1* Qunzhi Hua 1* Xinyu Luo 1* Qiming Wu 1*- 1 Anhui University of Science and Technology, Huainan, China
- 2 Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
- 3 Purple Mountain Observatory, Chinese Academy of Sciences (CAS), Nanjing, Jiangsu Province, China
- 4 School of Physics and Electronics, Hunan Normal University, Changsha, Hunan Province, China
It remains challenging to systematically survey nearby diffuse dwarf galaxies and address the formation mechanism of this population distinguishing from regular ones. We carry out a pilot search for these galaxies in the COSMOS field using the deep HST /F814W imaging data. We report three diffuse dwarf galaxies satisfying the criteria: (1) redshift z < 0.2, (2) effective radius r e > 1. 0, and (3) central surface brightness µ 0 > 24 mag arcsec -2 . Two of the three galaxies, COSMOS-UDG1 and COSMOS-UDG2, are recognized as ultra-diffuse galaxies (UDGs) with redshift z = 0.130 and 0.049, respectively. The third galaxy, COSMOS-dw1, is spectroscopically confirmed as a dwarf galaxy at z = 0.004. We derive the physical properties through fitting their spectral energy distributions (SEDs) extracted from deep multiwavelength observations. COSMOS-dw1 has a stellar mass of 5.6 +2.5 -2.7 × 10 6 M , harboring neutral hydrogen gas of mass 4.90 ± 0.90 × 10 6 M , hinting that this galaxy may be in the nascent stages of quenching. The estimated dynamical mass of 3.4 × 10 7 M further suggests that COSMOS-dw1 is predominantly of dark matter. COSMOS-UDG1 and COSMOS-UDG2 exhibit comparable stellar masses of ∼ 2 × 10 8 M . Notably, COSMOS-UDG1 is younger and more metal-rich than COSMOS-UDG2 and COSMOS-dw1. Conversely, COSMOS-UDG2 and COSMOS-dw1 have similar stellar metallicities, yet COSMOS-UDG2 is older than COSMOS-dw1. All three galaxies adhere to the stellar mass-metallicity relation (MZR) for dwarf galaxies in the local Universe, implying they belong to the dwarf galaxy population.
Keywords: galaxy formation, Galaxy evolution, COSMOS field, Ultra-diffuse galaxies, dwarf galaxies, extragalactic astronomy
Received: 14 Jan 2025; Accepted: 12 Feb 2025.
Copyright: © 2025 Shi, Zheng, Pan, Luo, Deng, Hua, Luo and Wu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
DongDong Shi, Anhui University of Science and Technology, Huainan, China
XianZhong Zheng, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 201210, China
Zhizheng Pan, Purple Mountain Observatory, Chinese Academy of Sciences (CAS), Nanjing, 210008, Jiangsu Province, China
Yu Luo, School of Physics and Electronics, Hunan Normal University, Changsha, 410081, Hunan Province, China
Hongxia Deng, Anhui University of Science and Technology, Huainan, China
Qunzhi Hua, Anhui University of Science and Technology, Huainan, China
Xinyu Luo, Anhui University of Science and Technology, Huainan, China
Qiming Wu, Anhui University of Science and Technology, Huainan, China
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