2025/11/26 by Paudel, Sanjaya, Sabiu, Cristiano G., Yoon, Suk-Jin +4
Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Astronomy and Astrophysical Research #Stellar, planetary, and galactic studies
paper · doi:10.48550/arxiv.2511.21010
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 non-nucleated dEs remain unresolved. Using a state-of-the-art machine learning framework, we systematically scan the Virgo cluster region (15\arcdeg × 20\arcdeg centered at R.A. = 187.2\arcdeg and Dec. = 9.6\arcdeg) and construct the largest homogeneous sample of dEs (of total 2,123) with robust nucleus classifications. We find that nucleated dEs are more spatially clustered and exhibit a stronger association with massive galaxies than their non-nucleated counterparts. This suggests that most nucleated dEs likely formed alongside massive galaxies within the cluster (i.e, the in-situ formation). In contrast, non-nucleated 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 non-nucleated 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.