Revisiting the globular clusters of NGC1052-DF2

Abstract

The ultra-diffuse galaxy (UDG) NGC1052-DF2 has captured the interest of astronomers ever since the low velocity dispersion measured from ten globular clusters (GCs) suggested a low dark matter fraction. Also, its GC system was found to be unusually bright, with a GC luminosity function peak at least one magnitude brighter than expected for a galaxy at a distance of 20 Mpc. In this work we present an updated view of the GC system of NGC1052-DF2. We analysed archival MUSE data of NGC1052-DF2 to confirm the membership of four additional GCs based on their radial velocities, thereby raising the number of spectroscopically confirmed GCs to 16. We measured the ages and metallicities of 11 individual GCs, finding them to be old ($>9$ Gyr) and with a range of metallicities from [M/H] = $-0.7$ to $-1.8$ dex. The majority of GCs are found to be more metal-poor than the host galaxy, with some metal-rich GCs sharing the metallicity of the host ([M/H] = $-$1.09${}_{-0.07}^{+0.09}$ dex). The host galaxy shows a flat age and metallicity gradient out to 1 $R_{\text{e}}$. Using a distance measurement based on the internal GC velocity dispersions ($D=16.2$ Mpc), we derived photometric GC masses and find that the peak of the GC mass function compares well with that of the Milky Way. From updated GC velocities, we estimated the GC system velocity dispersion of NGC1052-DF2 with a simple kinematic model and find ${\sigma }_{\text{GCS}}=14.86_{-2.83}^{+3.89}$ km s${}^{-1}$. However, this value is reduced to ${\sigma }_{\text{GCS}}=8.63_{-2.14}^{+2.88}$ km s${}^{-1}$ when the GC that has the highest relative velocity based on a low S/N spectrum is considered an interloper. We discuss the possible origin of NGC1502-DF2, taking the lower distance, spread in GC metallicities, flat stellar population profiles, and dynamical mass estimate into consideration.

13 pages, 10 figures, updated to version accepted for publication in A&A

References in corpus (35)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• A direct empirical proof of the existence of dark matter
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• 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
• The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early Type Galaxies
• NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
• A second galaxy missing dark matter in the NGC1052 group
• A new library of theoretical stellar spectra with scaled-solar and alpha-enhanced mixtures
• Galactic Dark Matter Halos and Globular Cluster Populations. III: Extension to Extreme Environments
• From Tidal Dwarf Galaxies to Satellite Galaxies
• Still Missing Dark Matter: KCWI High-Resolution Stellar Kinematics of NGC1052-DF2
• Identification of old tidal dwarfs near early-type galaxies from deep imaging and HI observations
• The Next Generation Virgo Cluster Survey (NGVS). XXX. Ultra-Diffuse Galaxies and their Globular Cluster Systems
• The Preferential Tidal Stripping of Dark Matter versus Stars in Galaxies
• A trail of dark matter-free galaxies from a bullet dwarf collision
• The ultra-diffuse galaxy NGC 1052-DF2 with MUSE: II. The population of DF2: stars, clusters and planetary nebulae
• Ultra-diffuse galaxies without dark matter
• Observational Properties of Ultra-Diffuse Galaxies in the Field: Field-UDGs are Predominantly Blue and Starforming
• A Tip of the Red Giant Branch Distance of $22.1\pm 1.2$ Mpc to the Dark Matter Deficient Galaxy NGC1052-DF2 from 40 Orbits of Hubble Space Telescope Imaging
• Tidal dwarf galaxies in cosmological simulations
• An old, metal-poor globular cluster in Sextans A and the metallicity floor of globular cluster systems
• The first detection of ultra-diffuse galaxies in the Hydra I cluster from VEGAS survey
• Ages, Metallicities, and [alpha/Fe] ratios of globular clusters in NGC 147, NGC 185, and NGC 205
• An Ultra diffuse Galaxy in the NGC 5846 group from the VEGAS survey
• On the Stellar Kinematics and Mass of the Virgo Ultra-Diffuse Galaxy VCC 1287
• The SLUGGS survey: Globular cluster stellar population trends from weak absorption lines in stacked spectra
• The ACS Fornax Cluster Survey. III. Globular Cluster Specific Frequencies of Early-Type Galaxies
• Nuclear star cluster formation in star-forming dwarf galaxies
• The Globular Cluster Population of NGC 1052-DF2: Evidence for Rotation
• Looking into the faintEst WIth MUSE (LEWIS): on the nature of ultra-diffuse galaxies in the Hydra-I cluster.I. Project description and preliminary results
• Stellar content, planetary nebulae, and globular clusters of [KKS2000]04 (NGC1052-DF2)
• Ultra-deep imaging of NGC1052-DF2 and NGC1052-DF4 to unravel their origins
• Signs of `Everything Everywhere All At Once' formation in low surface brightness globular cluster-rich dwarf galaxies
• Challenges in modeling the dark matter halo of NGC 1052-DF2: Cored versus cuspy halo models

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