Low Metallicities and Old Ages for Three Ultra-diffuse Galaxies in the Coma Cluster

Gu, Meng; Conroy, Charlie; Law, David R.; Dokkum, Pieter van; Yan, Renbin; Wake, David A.; Bundy, Kevin; Merritt, Allison; Abraham, Roberto; Zhang, Jielai; Bershady, Matthew A.; Bizyaev, Dmitry; Brinkmann, J.; Drory, Niv; Grabowski, Kathleen; Masters, Karen L.; Pan, Kaike; Parejko, John K.; Weijmans, Anne-Marie; Zhang, Kai

doi:10.3847/1538-4357/aabbae

Cited by 83 publications

(87 citation statements)

References 76 publications

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“…Only about a dozen higher surface brightness Coma UDGs have measured spectroscopic stellar population properties ( Ferré-Mateu et al (2018); Ruiz-Lara et al (2018); Gu et al (2018); Chilingarian et al (2019)). These studies generally found intermediate-to-old ages and low metallicities.…”

Section: Udg Stellar Massesmentioning

confidence: 99%

Globular clusters in Coma cluster ultra-diffuse galaxies (UDGs): evidence for two types of UDG?

Forbes

Alabi

Romanowsky

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Ultra diffuse galaxies (UDGs) reveal extreme properties. Here we compile the largest study to date of 85 globular cluster (GC) systems around UDGs in the Coma cluster, using new deep ground-based imaging of the known UDGs and existing imaging from the Hubble Space Telescope of their GC systems. We find that the richness of GC systems in UDGs generally exceeds that found in normal dwarf galaxies of the same stellar mass. These GC-rich UDGs imply halos more massive than expected from the standard stellar mass-halo mass relation. The presence of such overly massive halos presents a significant challenge to the latest simulations of UDGs in cluster environments. In some exceptional cases, the mass in the GC system is a significant fraction of the stellar content of the host galaxy. We find that rich GC systems tend to be hosted in UDGs of lower luminosity, smaller size and fainter surface brightness. Similar trends are seen for normal dwarf galaxies in the Coma cluster. A toy model is presented in which the GC-rich UDGs are assumed to be 'failed' galaxies within massive halos that have largely old, metal-poor, alpha-element enhanced stellar populations. On the other hand, GC-poor UDGs are more akin to normal, low surface brightness dwarfs that occupy less massive dark matter halos. Additional data on the stellar populations of UDGs with GC systems will help to further refine and test this simplistic model.

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Section: Udg Stellar Massesmentioning

confidence: 99%

Globular clusters in Coma cluster ultra-diffuse galaxies (UDGs): evidence for two types of UDG?

Forbes

Alabi

Romanowsky

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…In Figure 8 we compare the luminosityweighted age distribution of galaxies in our sample to that of UDGs observed in the Coma (Gu et al 2018;Ruiz-Lara et al 2018;Ferré-Mateu et al 2018) and Virgo (Pandya et al 2018) clus- Considering that we only have luminosityweighted ages, the results from the our analysis are expected to be biased toward the youngest populations within a galaxy. Therefore, a few different, non-exclusive scenarios can explain the additional fraction of UDGs with young ages.…”

Section: The Luminosity-weighted Ages Of Field Udgsmentioning

confidence: 99%

“…Prole et al 2019), are available for many UDGs but are of limited value in determining the properties of the stellar populations, while spectroscopy, which can provide the necessary information, is only available for a small number of galaxies (e.g. Martínez-Delgado et al 2016;Kadowaki et al 2017;Ruiz-Lara et al 2018;Ferré-Mateu et al 2018;Gu et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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One Hundred SMUDGes in S-PLUS: Ultra-diffuse Galaxies Flourish in the Field

Barbosa

Zaritsky

Donnerstein

et al. 2020

ApJS

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We present the first systematic study of the stellar populations of ultra-diffuse galaxies (UDGs) in the field, integrating the large area search and characterization of UDGs by the SMUDGes survey with the twelve-band optical photometry of the S-PLUS survey. Based on Bayesian modeling of the optical colors of UDGs, we determine the ages, metallicities and stellar masses of 100 UDGs distributed in an area of ∼ 330 deg 2 in the Stripe 82 region. We find that the stellar masses and metallicities of field UDGs are similar to those observed in clusters and follow the trends previously defined in studies of dwarf and giant galaxies. However, field UDGs have younger luminosityweighted ages than do UDGs in clusters. We interpret this result to mean that field UDGs have more extended star formation histories, including some that continue to form stars at low levels to the present time. Finally, we examine stellar population 2 Barbosa et al.scaling relations that show that UDGs are, as a population, similar to other low-surface brightness galaxies.

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“…Koleva et al 2008;Larsen et al 2017;Wilkinson et al 2017;Conroy et al 2018) or even by simultaneously fitting both photometry and spectroscopy to fully utilise the information contained in the spectroscopy (Leja et al 2017). A previous example of combining the stellar population constraints from optical photometry and spectroscopy can be found in Gu et al (2018) who used both to place stronger constraints on the old ages of three ultra-diffuse galaxies.…”

Section: Ages From Combining Photometry and Spectroscopymentioning

confidence: 99%

The SLUGGS survey: measuring globular cluster ages using both photometry and spectroscopy

Usher

Brodie

Forbes

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Globular cluster ages provide both an important test of models of globular cluster formation and a powerful method to constrain the assembly history of galaxies. Unfortunately, measuring the ages of unresolved old stellar populations has proven challenging. Here, we present a novel technique that combines optical photometry with metallicity constraints from near-infrared spectroscopy in order to measure ages. After testing the method on globular clusters in the Milky Way and its satellite galaxies, we apply our technique to three massive early-type galaxies using data from the SLUGGS Survey. The three SLUGGS galaxies and the Milky Way show dramatically different globular cluster age and metallicity distributions, with NGC 1407 and the Milky Way showing mostly old globular clusters while NGC 3115 and NGC 3377 show a range of globular ages. This diversity implies different galaxy formation histories and that the globular cluster optical colour-metallicity relation is not universal as is commonly assumed in globular cluster studies. We find a correlation between the median age of the metal rich globular cluster populations and the age of the field star populations, in line with models where globular cluster formation is a natural outcome of high intensity star formation.

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Low Metallicities and Old Ages for Three Ultra-diffuse Galaxies in the Coma Cluster

Cited by 83 publications

References 76 publications

Globular clusters in Coma cluster ultra-diffuse galaxies (UDGs): evidence for two types of UDG?

Globular clusters in Coma cluster ultra-diffuse galaxies (UDGs): evidence for two types of UDG?

One Hundred SMUDGes in S-PLUS: Ultra-diffuse Galaxies Flourish in the Field

The SLUGGS survey: measuring globular cluster ages using both photometry and spectroscopy

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