The Astrophysical Journal, 995:178 (8pp), 2025 December 20
https://doi.org/10.3847/1538-4357/ae2097
Sanjaya Paudel1,2, Cristiano G. Sabiu3, Suk-Jin Yoon1, Daya Nidhi Chhatkuli4, Woong-Bae G. Zee5, Jaewon Yoo6, and Binod Adhikari7
1 Department of Astronomy & Center for Galaxy Evolution Research, Yonsei University, Seoul 03722, Republic of Korea; sjyoon0691@yonsei.ac.kr
2 Nepal Astronomical Society, Kathmandu, Nepal
3 Natural Science Research Institute (NSRI), University of Seoul, Seoul 02504, Republic of Korea
4 Department of Physics, Tri-Chandra Multiple Campus, Tribhuvan University, Kathmandu, Nepal
5 School of Liberal Studies, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea
6 Korea Astronomy and Space Science Institute (KASI), Daedeokdae-ro, Daejeon 34055, Republic of Korea
7 Department of Physics, St. Xavier’s College, Tribhuvan University, Kathmandu, Nepal Received 2025 October 2; revised 2025 November 11; accepted 2025 November 13; published 2025 December 15
Abstract
Dwarf elliptical galaxies (dEs) are the dominant population in galaxy clusters and serve as ideal probes for
studying the environmental impact on galactic evolution. A substantial fraction of dEs are known to harbor central nuclei, which are among the densest stellar systems in the Universe. The large-scale distribution and the underlying origin of nucleated and nonnucleated dEs remain unresolved. Using a state-of-the-art machine learning framework, we systematically scan the Virgo cluster region (15° × 20° centered at R. A. = 187°.2 and
decl. = 9°. 6) and construct the largest homogeneous sample of dEs (a total of 2123) with robust nucleus
classifications. We find that nucleated dEs are more spatially clustered and exhibit a stronger association with
massive galaxies than their nonnucleated counterparts. This suggests that most nucleated dEs likely formed
alongside massive galaxies within the cluster (i.e., the in situ formation). In contrast, nonnucleated dEs are more widely distributed across the cluster and align more closely with Virgo’s global potential well, as traced by the cluster’s hot gas. This indicates that most nonnucleated dEs originated outside the cluster (i.e., the ex situ formation) and were later accreted and redistributed within it. Our findings shed new light on how dEs and their central nuclei form and evolve.
