A Closer Look at an Unusual Ultra-Diffuse Galaxy

Abstract

We present a spectroscopic study of the ``Disco Ball'' (SMDG0038365-064207), a rotationally-supported, red-sequence, ultra-diffuse galaxy (UDG) with a nuclear star cluster (NSC), multiple stellar clusters, and active star-forming regions using data obtained with KCWI on the Keck II Telescope. We calculate that the galaxy hosts $34\pm 11$ ``globular" clusters. Kinematic measurements confirm rotation with a peak rotational velocity of at least 53km s${}^{-1}$ and a dynamical mass within $r_{\mathrm{e}}$ of at least $10^{9.3\pm 0.2}{M}_{\odot }$. Our dynamical estimates of the halo mass are consistent with that obtained using the number of globular clusters and together suggest $M_{\mathrm{h}}=10^{11.1\pm 0.2}{M}_{\odot }$. The NSC may exhibit signatures of weak AGN activity. Our findings challenge two common assumptions: (1) clusters in some UDGs may be younger than generally assumed, and thus more luminous than standard globular clusters (GCs), affecting GC counts and the derived GC luminosity function in these UDGs, and (2) quiescent UDGs can be rotationally supported, making kinematic measurements viewing-angle dependent in such cases. The Disco Ball, while unremarkable in mass, size, projected structural properties, or color, reveals surprising complexity, highlighting the need for detailed studies of more UDGs.

Submitted to ApJ. 20 pages, 8 figures. Comments are welcome

References in corpus (41)

• The NumPy array: a structure for efficient numerical computation
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• Stellar Population Inference with Prospector
• The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
• UV-extended E-MILES stellar population models: young components in massive early-type galaxies
• Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
• Nuclear Star Clusters
• NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
• Full spectrum fitting with photometry in pPXF: stellar population versus dynamical masses, non-parametric star formation history and metallicity for 3200 LEGA-C galaxies at redshift z~0.8
• The Baryon Content of Extremely Low Mass Dwarf Galaxies
• The life cycle of star cluster in a tidal field
• Clues to Nuclear Star Cluster Formation from Edge-on Spirals
• Galactic Dark Matter Halos and Globular Cluster Populations. III: Extension to Extreme Environments
• Extensive Globular Cluster Systems Associated with Ultra Diffuse Galaxies in the Coma Cluster
• A First Attempt to Calibrate the Baryonic Tully-Fisher Relation with Gas Dominated Galaxies
• The Formation of Ultra-Diffuse Galaxies in Clusters
• The HST/ACS Coma Cluster Survey. X. Nuclear star clusters in low-mass early-type galaxies: scaling relations
• The Next Generation Virgo Cluster Survey (NGVS). XXX. Ultra-Diffuse Galaxies and their Globular Cluster Systems
• Robust HI kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario
• The Formation of Isolated Ultra-Diffuse Galaxies in Romulus25
• The evolution of ultra-diffuse galaxies in nearby galaxy clusters from the Kapteyn IAC WEAVE INT Clusters Survey ($\text{KIWICS}$)
• Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes). V. The Complete SMUDGes Catalog and the Nature of Ultra-Diffuse Galaxies
• Implications for Galaxy Formation Models from Observations of Globular Clusters around Ultra-Diffuse Galaxies
• Origin and evolution of ultra-diffuse galaxies in different environments
• One hundred SMUDGes in S-PLUS: ultra-diffuse galaxies flourish in the field
• A Complex Luminosity Function for the Anomalous Globular Clusters in NGC1052-DF2 and NGC1052-DF4
• Systematically Measuring Ultra Diffuse Galaxies in HI: Results from the Pilot Survey
• The globular clusters and star formation history of the isolated, quiescent ultra-diffuse galaxy DGSAT I
• The Next Generation Virgo Cluster Survey (NGVS). XXXV. First Kinematical Clues of Overly-Massive Dark Matter Halos in Several Ultra-Diffuse Galaxies in the Virgo Cluster
• On the Properties of Spectroscopically-Confirmed Ultra-Diffuse Galaxies Across Environment
• Hyper Suprime-Cam Low Surface Brightness Galaxies II: A Hubble Space Telescope Study of the Globular Cluster Systems of Ultra-Diffuse Galaxies in Groups
• Photometric Mass Estimation and the Stellar Mass-Halo Mass Relation for Low Mass Galaxies
• Global dynamic scaling relations of HI-rich ultra-diffuse galaxies
• Looking into the faintEst WIth MUSE (LEWIS): Exploring the nature of ultra-diffuse galaxies in the Hydra-I cluster II. Stellar kinematics and dynamical masses
• All Puffed Up: Exploring Ultra-diffuse Galaxy Origins through Galaxy Interactions
• Signs of `Everything Everywhere All At Once' formation in low surface brightness globular cluster-rich dwarf galaxies
• An Unexplained Origin for the Unusual Globular Cluster System in the Ultra-diffuse Galaxy FCC 224
• A candidate dark matter deficient dwarf galaxy in the Fornax cluster identified through overluminous star clusters
• Properties of Nuclear Star Clusters in Low Surface Brightness Galaxies
• Discovery of Two Ultra-Diffuse Galaxies with Unusually Bright Globular Cluster Luminosity Functions via a Mark-Dependently Thinned Point Process (MATHPOP)
• A systematic analysis of star cluster disruption by tidal shocks -- II. Predicting star cluster dissolution rates from a time-series analysis of their tidal histories