The Next Generation Virgo Cluster Survey. XXXIII. Stellar Population Gradients in the Virgo Cluster Core Globular Cluster System

Abstract

We present a study of the stellar populations of globular clusters (GCs) in the Virgo Cluster core with a homogeneous spectroscopic catalog of 692 GCs within a major axis distance $R_{\mathrm{maj}}=$ 840 kpc from M87. We investigate radial and azimuthal variations in the mean age, total metallicity, [Fe/H], and $\alpha$-element abundance, of blue (metal-poor) and red (metal-rich) GCs using their co-added spectra. We find that the blue GCs have a steep radial gradient in [Z/H] within $R_{\mathrm{maj}}=$ 165 kpc, with roughly equal contributions from [Fe/H] and [$\alpha$/Fe], and flat gradients beyond. By contrast, the red GCs show a much shallower gradient in [Z/H], which is entirely driven by [Fe/H]. We use GC-tagged Illustris simulations to demonstrate an accretion scenario where more massive satellites (with more metal- and $\alpha$-rich GCs) sink further into the central galaxy than less massive ones, and where the gradient flattening occurs because of the low GC occupation fraction of low-mass dwarfs disrupted at larger distances. The dense environment around M87 may also cause the steep [$\alpha$/Fe] gradient of the blue GCs, mirroring what is seen in the dwarf galaxy population. The progenitors of red GCs have a narrower mass range than those of blue GCs, which makes their gradients shallower. We also explore spatial inhomogeneity in GC abundances, finding that the red GCs to the northwest of M87 are slightly more metal-rich. Future observations of GC stellar population gradients will be useful diagnostics of halo merger histories.

22 pages, 8 figures, 4 tables, accepted for publication in ApJ

References in corpus (40)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• Properties of galaxies reproduced by a hydrodynamic simulation
• The Atlas3D Project - XXX. Star formation histories and stellar population scaling relations of early-type galaxies
• The Atlas3D project -- XXIX. The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images
• The ACS Virgo Cluster Survey XV. The Formation Efficiencies of Globular Clusters in Early-Type Galaxies: The Effects of Mass and Environment
• The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early Type Galaxies
• The Importance of Mergers for the Origin of Intracluster Stars in Cosmological Simulations of Galaxy Clusters
• The Gaia-ESO Survey: the Galactic Thick to Thin Disc transition
• The Burrell Schmidt Deep Virgo Survey: Tidal Debris, Galaxy Halos, and Diffuse Intracluster Light in the Virgo Cluster
• Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting
• Diffuse Optical Light in Galaxy Clusters II: Correlations with Cluster Properties
• Planetary nebulae as tracers of galaxy stellar populations
• The Extended Virgo Cluster Catalog
• Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca
• The E-MOSAICS project: tracing galaxy formation and assembly with the age-metallicity distribution of globular clusters
• A Spectacular H$\alpha$ Complex in Virgo: Evidence for a Collision Between M86 and NGC 4438 and Implications for Collisional ISM Heating of Ellipticals
• Dark Matter Halos in Galaxies and Globular Cluster Populations. II: Metallicity and Morphology
• A spectroscopic survey of dwarf galaxies in the Coma Cluster: Stellar populations, environment and downsizing
• The initial mass function of a massive relic galaxy
• The build-up of the cD halo of M87 - evidence for accretion in the last Gyr
• Formation histories of stars, clusters and globular clusters in the E-MOSAICS simulations
• The Next Generation Virgo cluster Survey. V. modelling the dynamics of M87 with the Made-to-Measure method
• The Fornax3D project: Tracing the assembly history of the cluster from the kinematic and line-strength maps
• Kinematics and Stellar Populations of Low-Luminosity Early-Type Galaxies in the Abell 496 Cluster
• The Globular Cluster System of M60 (NGC 4649). II. Kinematics of the Globular Cluster System
• Virgo's Intracluster Globular Clusters as Seen by the Advanced Camera for Surveys
• A Subaru/Suprime-Cam wide-field survey of globular cluster populations around M87 - II: Colour and spatial distribution
• The difference in metallicity distribution functions of halo stars and globular clusters as a function of galaxy type: A tracer of globular cluster formation and evolution
• Spectrophotometry with Hectospec, the MMT's Fiber-Fed Spectrograph
• The SLUGGS survey: Globular cluster stellar population trends from weak absorption lines in stacked spectra
• The Planetary Nebula Spectrograph survey of S0 galaxy kinematics. Data and Overview
• To the Edge of M87 and Beyond: Spectroscopy of Intracluster Globular Clusters and Ultra Compact Dwarfs in the Virgo Cluster
• Compact stellar systems and cluster environments
• Globular Clusters As Tracers of Fine Structure in the Dramatic Shell Galaxy NGC 474
• Deriving ages and horizontal branch properties of integrated stellar populations
• A discrete chemo-dynamical model of M87's globular clusters: Kinematics extending to ~ 400 kpc
• A Wide-field Photometric Survey of Globular Clusters in the Peculiar Early-type Galaxy M85
• Is there substructure around M87?
• Substructure in the Globular Cluster Populations of the Virgo Cluster Elliptical Galaxies M84 and M86
• Mysterious Globular Cluster System of the Peculiar Massive Galaxy M85

Cited by in corpus (3)

• An evolutionary continuum from nucleated dwarf galaxies to star clusters
• A Photometric Survey of Globular Cluster Systems in Brightest Cluster Galaxies
• Properties of Globular Clusters in Galaxy Clusters: Sensitivity from the Formation and Evolution of Globular Clusters