SIMBAD references

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$\mathop{.}\limits^{\unicode{x000b0}}$2 and decl. = 9$\mathop{.}\limits^{\unicode{x000b0}}$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.