skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • The Next Generation Virgo Cluster Survey (NGVS). XXXV. First Kinematical Clues of Overly Massive Dark Matter Halos in Several Ultradiffuse Galaxies in the Virgo Cluster
Title: The Next Generation Virgo Cluster Survey (NGVS). XXXV. First Kinematical Clues of Overly Massive Dark Matter Halos in Several Ultradiffuse Galaxies in the Virgo Cluster
Abstract We present Keck/DEIMOS spectroscopy of the first complete sample of ultradiffuse galaxies (UDGs) in the Virgo cluster. We select all UDGs in Virgo that contain at least 10 globular cluster (GC) candidates and are more than 2.5 σ outliers in scaling relations of size, surface brightness, and luminosity (a total of 10 UDGs). We use the radial velocity of their GC satellites to measure the velocity dispersion of each UDG. We find a mixed bag of galaxies, from one UDG that shows no signs of dark matter, to UDGs that follow the luminosity–dispersion relation of early-type galaxies, to the most extreme examples of heavily dark matter–dominated galaxies that break well-known scaling relations such as the luminosity–dispersion or U-shaped total mass-to-light ratio relations. This is indicative of a number of mechanisms at play forming these peculiar galaxies. Some of them may be the most extended version of dwarf galaxies, while others are so extreme that they seem to populate dark matter halos consistent with that of the Milky Way or even larger. Even though Milky Way stars and other GC interlopers contaminating our sample of GCs cannot be fully ruled out, our assessment of this potential problem and simulations indicate that the probability is low and, if present, unlikely to be enough to explain the extreme dispersions measured. Further confirmation from stellar kinematics studies in these UDGs would be desirable. The lack of such extreme objects in any of the state-of-the-art simulations opens an exciting avenue of new physics shaping these galaxies.  more » « less
Award ID(s):
1945310 2206498 2206328
PAR ID:
10430702
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
951
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
77
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, Monthly Notices of the Royal Astronomical Society)
    ABSTRACT The velocity dispersion of globular clusters (GCs) around ultra-diffuse galaxies (UDGs) in the Virgo cluster spans a wide range, including cases where GC kinematics suggest haloes as massive as (or even more massive than) that of the Milky Way around these faint dwarfs. We analyse the catalogues of GCs derived in post-processing from the TNG50 cosmological simulation to study the GC system kinematics and abundance of simulated UDGs in galaxy groups and clusters. UDGs in this simulation reside exclusively in dwarf-mass haloes with M200 ≲ 1011.2 M⊙. When considering only GCs gravitationally bound to simulated UDGs, we find GCs properties that overlap well with several observational measurements for UDGs. In particular, no bias towards overly massive haloes is inferred from the study of bound GCs, confirming that GCs are good tracers of UDG halo mass. However, we find that contamination by intracluster GCs may, in some cases, substantially increase velocity dispersion estimates when performing projected mock observations of our sample. We caution that targets with less than 10 GC tracers are particularly prone to severe uncertainties. Measuring the stellar kinematics of the host galaxy should help confirm the unusually massive haloes suggested by GC kinematics around some UDGs. 
    more » « less
  2. ; ; ; ; ; ; ; ; (, American Astronomical Society Meeting #241, id. 260.04. Bulletin of the American Astronomical Society, Vol. 55, No. 2 e-id 2023n2i260p04)
    We use deep Hubble Space Telescope imaging to study the evolutionary state of of the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615. Using the tip of the red giant branch method, we pinpoint the galaxy's location with Virgo to be on the far side of the cluster, near the Virgo virial radius. When combined with the galaxy's measured line of sight velocity, we find the galaxy to be on an outbound orbit, having likely passed near the cluster core within the past billion years. Given the galaxy's largely undisturbed morphology, we argue that the galaxy has experienced no recent and sudden transformation into a UDG due to the cluster potential, but rather is a long-lived UDG whose relatively wide orbit and large dynamical mass protect it from stripping and destruction by Virgo cluster tides. Our Hubble imaging resolves individual globular clusters within VCC 615 down to a limiting half-light radius of 1 pc, allowing for a clean determination of the size distribution and luminosity function of the galaxy's globular cluster population. The total mass of the galaxy derived from the size of its globular cluster population is comparable to our previous work estimate from the mass from the globular cluster kinematics. Finally, we also derive the structural properties of the galaxy's nucleus and find them similar to the properties of ultracompact galaxies (UCDs) in the Virgo core, suggesting a dynamical link between UCDs and nucleated UDGs in cluster environments. 
    more » « less
  3. ; ; ; ; ; ; ; (, The Astrophysical Journal)
    Abstract 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 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 radiiRh > 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. 
    more » « less
  4. (, Open Journal of Astrophysics)
    I compare the dark matter content within stellar half-mass radius expected in a $$\Lambda$$CDM-based galaxy formation model with existing observational estimates for the observed dwarf satellites of the Milky Way and ultra-diffuse galaxies (UDGs). The model reproduces the main properties and scaling relations of dwarf galaxies, in particular their stellar mass-size relation. I show that the model also reproduces the relation between the dark matter mass within the half-mass radius, $$M_{\rm dm}( 
    more » « less
  5. ; ; ; ; ; ; ; ; ; ; et al (, Monthly Notices of the Royal Astronomical Society)
    ABSTRACT Recent studies of ultra-diffuse galaxies (UDGs) have shown their globular cluster (GC) systems to be central in unveiling their remarkable properties and halo masses. Deep Hubble Space Telescope imaging revealed 54 GC candidates around the UDG NGC5846_UDG1 (UDG1), with a remarkable 13 per cent of the stellar light contained in the GC system. We present a kinematic analysis of UDG1’s GC system from observations with the integral field spectrograph Keck Cosmic Web Imager on the Keck II telescope. We measure recessional velocities for 19 GCs, confirming them as members of UDG1, giving a total of 20 confirmed GCs when combined with literature. Approximately, 9 per cent of the stellar light are contained just in the confirmed GCs. We determine the GC system’s velocity dispersion to be $$\sigma _{\rm GC}$$ = 29.8$$^{+6.4}_{-4.9}$$ km s$$^{-1}$$. We find that $$\sigma _{\rm GC}$$ increases with increasing magnitude, consistent with predictions for a GC system that evolved under the influence of dynamical friction. The GC system velocity dispersion is constant out to $${\sim} 1R_{\rm eff}$$. Using $$\sigma _{\rm GC}$$, we calculate $$M_{\rm dyn}$$ = $$2.09^{+1.00}_{-0.64}\times 10^{9}$$ M$$_{\odot }$$ as the dynamical mass enclosed within $$\sim$$2.5 kpc. The dark matter halo mass suggested by the GC number–halo mass relationship agrees with our dynamical mass estimate, implying a halo more massive than suggested by common stellar mass–halo mass relationships. UDG1, being GC-rich with a massive halo, fits the picture of a failed galaxy. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email