The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615

We use Hubble Space Telescope imaging to study the globular cluster system of the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615. We select globular cluster candidates through a combination of size and color, while simultaneously rejecting contamination from background galaxies that would be unreso...

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Main Authors: J. Christopher Mihos, Patrick R. Durrell, Elisa Toloba, Eric W. Peng, Sungsoon Lim, Patrick Côté, Puragra Guhathakurta, Laura Ferrarese
Format: Article
Language:English
Published: IOP Publishing 2024-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/ad99cd
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author J. Christopher Mihos
Patrick R. Durrell
Elisa Toloba
Eric W. Peng
Sungsoon Lim
Patrick Côté
Puragra Guhathakurta
Laura Ferrarese
author_facet J. Christopher Mihos
Patrick R. Durrell
Elisa Toloba
Eric W. Peng
Sungsoon Lim
Patrick Côté
Puragra Guhathakurta
Laura Ferrarese
author_sort J. Christopher Mihos
collection DOAJ
description We use Hubble Space Telescope imaging to study the globular cluster system of the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615. We select globular cluster candidates through a combination of size and color, while simultaneously rejecting contamination from background galaxies that would be unresolved in ground-based imaging. Our sample of globular cluster candidates is essentially complete down to a limiting magnitude of F814W = 24.0, ≈90% down the globular cluster luminosity function (GCLF). We estimate a total globular cluster population for VCC 615 of ${N}_{{\rm{GC}}}=25.{1}_{-5.4}^{+6.5}$ , resulting in a specific frequency of ${S}_{N}=55.{5}_{-12.0}^{+14.5}$ , quite high compared to normal galaxies of similar luminosity, but consistent with the large specific frequencies found in some other UDGs. The abundant cluster population suggests the galaxy is enshrouded by a massive dark halo, consistent with previous dynamical mass estimates using globular cluster kinematics. While the peak of the GCLF appears slightly brighter than expected (by ≈0.3–0.5 mag), this difference is comparable to the 0.3 mag uncertainty in the measurement, and we see no sign of an extremely luminous population of clusters similar to those detected in the UDGs NGC1054-DF2 and -DF4. However, we do find a relatively high fraction ( $3{2}_{-4}^{+5}$ %) of large clusters with half-light radii R _h  > 9 pc. The galaxy's offset nucleus appears photometrically distinct from the globular clusters, and is more akin to ultracompact dwarfs (UCDs) in Virgo. Over time, VCC615’s already diffuse stellar body may be further stripped by cluster tides, leaving the nucleus intact to form a new Virgo UCD.
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spelling doaj-art-e96278b23e73464ba58f01a0b2f532fe2025-08-20T02:25:44ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-0197819310.3847/1538-4357/ad99cdThe Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615J. Christopher Mihos0https://orcid.org/0000-0002-7089-8616Patrick R. Durrell1https://orcid.org/0000-0001-9427-3373Elisa Toloba2https://orcid.org/0000-0001-6443-5570Eric W. Peng3Sungsoon Lim4https://orcid.org/0000-0002-5049-4390Patrick Côté5Puragra Guhathakurta6https://orcid.org/0000-0001-8867-4234Laura Ferrarese7https://orcid.org/0000-0002-8224-1128Department of Astronomy, Case Western Reserve University , Cleveland OH 44106, USADepartment of Physics, Astronomy, Geophysics and Environmental Sciences, Youngstown State University , Youngstown, OH 44555, USADepartment of Physics and Astronomy, University of the Pacific , Stockton, CA 95211, USANOIRLab , 950 North Cherry Avenue, Tucson, AZ, 85719, USADepartment of Astronomy, Yonsei University , 50 Yonsei-ro Seodaemun-gu, Seoul, 03722, Republic of KoreaNational Research Council of Canada , Herzberg Astronomy and Astrophysics Program, Victoria, BC V9E 2E7, CanadaUCO/Lick Observatory, University of California Santa Cruz , Santa Cruz, CA 95064, USANational Research Council of Canada , Herzberg Astronomy and Astrophysics Program, Victoria, BC V9E 2E7, CanadaWe use Hubble Space Telescope imaging to study the globular cluster system of the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615. We select globular cluster candidates through a combination of size and color, while simultaneously rejecting contamination from background galaxies that would be unresolved in ground-based imaging. Our sample of globular cluster candidates is essentially complete down to a limiting magnitude of F814W = 24.0, ≈90% down the globular cluster luminosity function (GCLF). We estimate a total globular cluster population for VCC 615 of ${N}_{{\rm{GC}}}=25.{1}_{-5.4}^{+6.5}$ , resulting in a specific frequency of ${S}_{N}=55.{5}_{-12.0}^{+14.5}$ , quite high compared to normal galaxies of similar luminosity, but consistent with the large specific frequencies found in some other UDGs. The abundant cluster population suggests the galaxy is enshrouded by a massive dark halo, consistent with previous dynamical mass estimates using globular cluster kinematics. While the peak of the GCLF appears slightly brighter than expected (by ≈0.3–0.5 mag), this difference is comparable to the 0.3 mag uncertainty in the measurement, and we see no sign of an extremely luminous population of clusters similar to those detected in the UDGs NGC1054-DF2 and -DF4. However, we do find a relatively high fraction ( $3{2}_{-4}^{+5}$ %) of large clusters with half-light radii R _h  > 9 pc. The galaxy's offset nucleus appears photometrically distinct from the globular clusters, and is more akin to ultracompact dwarfs (UCDs) in Virgo. Over time, VCC615’s already diffuse stellar body may be further stripped by cluster tides, leaving the nucleus intact to form a new Virgo UCD.https://doi.org/10.3847/1538-4357/ad99cdGalaxy clustersGalaxy evolutionGlobular star clustersLow surface brightness galaxiesDwarf galaxies
spellingShingle J. Christopher Mihos
Patrick R. Durrell
Elisa Toloba
Eric W. Peng
Sungsoon Lim
Patrick Côté
Puragra Guhathakurta
Laura Ferrarese
The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615
The Astrophysical Journal
Galaxy clusters
Galaxy evolution
Globular star clusters
Low surface brightness galaxies
Dwarf galaxies
title The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615
title_full The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615
title_fullStr The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615
title_full_unstemmed The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615
title_short The Globular Cluster System of the Virgo Cluster Ultradiffuse Galaxy VCC 615
title_sort globular cluster system of the virgo cluster ultradiffuse galaxy vcc 615
topic Galaxy clusters
Galaxy evolution
Globular star clusters
Low surface brightness galaxies
Dwarf galaxies
url https://doi.org/10.3847/1538-4357/ad99cd
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