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This content will become publicly available on July 10, 2026

Title: A Wide-field Map of Ultracompact Dwarfs in the Coma Cluster
Abstract A data set of 23,351 globular clusters (GCs) and ultracompact dwarfs (UCDs) in the Coma cluster of galaxies was built using Hubble Space Telescope Advanced Camera for Surveys data. Based on the standard magnitude cut ofMV≤ −11, a total of 523 UCD candidates are found within this data set of compact stellar systems (CSS). From a color–magnitude diagram analysis built using this catalog, we find a clear mass–magnitude relation extending marginally into the UCD parameter space. The luminosity function defined by this data set shows an excess of sources at bright magnitudes, suggesting a bimodal formation scenario for UCDs. We estimate the number of UCDs with a different origin than GC to beNUCD≳ 32 ± 1. We derive the total number of CSS within the core (1 Mpc) of Coma to beNCSS≈ 69,400 ± 1400. The radial distribution of UCDs in Coma shows that, like GCs, UCDs agglomerate around three giant ellipticals: NGC 4874, NGC 4889, and IC 4051. We find UCDs are more centrally concentrated around these three ellipticals than GCs. IC 4051 has a satellite population of UCDs similar to NGC 4874 and NGC 4889. We estimate only ∼14% of UCDs inhabit the intracluster space (ICUCD) between galaxies in the region, in comparison to ∼24% for GCs (ICGC). We find red (metal-rich) UCDs are more likely located closer to a host galaxy, with blue (metal-poor) UCDs showing a greater dispersion and lower average density in the region.  more » « less
Award ID(s):
2019786
PAR ID:
10648135
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
AAS
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
988
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
1
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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