From star clusters to dwarf galaxies: The properties of dynamically hot stellar systems

Abstract

(Abridged) Objects with radii of 10 to 100 pc and masses in the range from 10^6 to 10^8 M_sun have been discovered during the past decade. These so-called ultra compact dwarf galaxies (UCDs) constitute a transition between classical star clusters and elliptical galaxies in terms of radii, relaxation times and V-band mass-to-light (M/L_V) ratios. Using new data, we find that the mass interval from 10^6 to 10^7 M_sun is of special interest, because within this range typical half-light radii and dynamical mass-to-light ratios begin to increase compared to globular clusters, the highest stellar densities are reached and typical median two-body relaxation times surpass a Hubble time. The M/L_V ratios of the UCDs turn out to be incompatible with the predictions from simple stellar population (SSP) models when using the canonical stellar initial mass function (IMF), although SSPs probably are good approximations to the real stellar populations in UCDs and the SSP models allow to account for metallicity effects on the M/L_V ratio. This provides evidence for the UCDs either having formed with an IMF different from the canonical one or containing dark matter. We emphasise that almost all pressure-supported stellar systems ranging from star clusters to massive elliptical galaxies have M/L_V ratios less than 10 M_sun/L_sun, and that only dSph satellite galaxies have M/L_V ratios greater than 100 M_sun/L_sun and therewith form exceptional systems.

arXiv comment26 pages, 15 figures, accepted for publication in MNRAS. Minor changes in the text and updates in the reference list in the replaced version

References in corpus (73)

• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• The Structure of Cold Dark Matter Halos
• On the variation of the Initial Mass Function
• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Dwarf Galaxies of the Local Group
• Evolutionary population synthesis: models, analysis of the ingredients and application to high-z galaxies
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• The ages and metallicities of galaxies in the local universe
• SparsePak: A Formatted Fiber Field Unit for The WIYN Telescope Bench Spectrograph. I. Design, Construction, and Calibration
• The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the fundamental plane of elliptical and lenticular galaxies
• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• Stellar population models of Lick indices with variable element abundance ratios
• Dynamical evolution of star clusters in tidal fields
• Resolved Massive Star Clusters in the Milky Way and its Satellites: Brightness Profiles and a Catalogue of Fundamental Parameters
• The Stellar Population Histories of Local Early-Type Galaxies. I. Population Parameters
• The Observed properties of Dark Matter on small spatial scales
• The Galactic disk mass-budget : I. stellar mass-function and density
• M31 Globular Clusters: Colors and Metallicities
• The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early Type Galaxies
• An upper limit to the masses of stars
• The dynamical distance and intrinsic structure of the globular cluster omega Centauri
• On the typical timescale for the chemical enrichment from SNeIa in Galaxies
• The ACS Virgo Cluster Survey. VII. Resolving the Connection Between Globular Clusters and Ultra-Compact Dwarf Galaxies
• A class of compact dwarf galaxies from disruptive processes in galaxy clusters
• The rates of Type Ia Supernovae. I. Analytical Formulations
• Compact Stellar Systems in the Fornax Cluster: Super-massive Star Clusters or Extremely Compact Dwarf Galaxies?
• The ACS Virgo Cluster Survey X. Half-light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation
• The early evolution of Globular Clusters: the case of NGC 2808
• The central region of the Fornax cluster -- II. Spectroscopy and radial velocities of member and background galaxies
• Homogeneous age dating of 55 Galactic globular clusters. Clues to the Galaxy formation mechanisms
• On the self-enrichment scenario of galactic globular clusters: Constraints on the IMF
• Evidence for a fundamental stellar upper mass limit from clustered star formation
• Evidence of Cosmic Evolution of the Stellar Initial Mass Function
• Global Relationships Among the Physical Properties of Stellar Systems
• Internal Dynamics, Structure and Formation of Dwarf Elliptical Galaxies: II. Rotating Versus Non-Rotating Dwarfs
• Globular Cluster Systems in Brightest Cluster Galaxies: Bimodal Metallicity Distributions and the Nature of the High-Luminosity Clusters
• Molecular Gas and Star Formation in the SAURON Early-type Galaxies
• The multiplicity of the subgiant branch of Omega Centauri: Evidence for prolonged star formation
• Galaxy threshing and the origin of ultra-compact dwarf galaxies in the Fornax cluster
• The Formation of Ultra-Compact Dwarf Galaxies
• Mayall II = G1 in M31: Giant Globular Cluster or Core of a Dwarf Elliptical Galaxy ?
• Ultra-Compact Dwarf Galaxies in the Fornax Cluster
• Explaining the Color Distributions of Globular Cluster Systems in Elliptical Galaxies
• A Dynamical Model for the Globular Cluster G1
• Internal Properties of Ultra-Compact Dwarf Galaxies in the Virgo Cluster
• Binding Energy and the Fundamental Plane of Globular Clusters
• Statistical Confirmation of a Stellar Upper Mass Limit
• Keck Spectroscopy of Globular Clusters around NGC 1399
• Nearby early-type galaxies with ionized gas. III. Analysis of line-strength indices with new stellar population models
• The dynamical evolution of stellar super-clusters
• The satellite distribution of M31
• Spectroscopic metallicities for Fornax UCDs, GCs and dE,Ns
• A highly abnormal massive star mass function in the Orion Nebula cluster and the dynamical decay of trapezia systems
• Ultra Compact Objects in the Fornax Cluster of Galaxies: Globular clusters or dwarf galaxies?
• The metal enrichment of the intracluster medium in hierarchical galaxy formation models
• Dynamical masses of ultra-compact dwarf galaxies in Fornax
• Fornax compact object survey FCOS: On the nature of Ultra Compact Dwarf galaxies
• The Globular Cluster Systems of Five Nearby Spiral Galaxies: New Insights from Hubble Space Telescope Imaging
• Dwarf galaxy formation induced by galaxy interactions
• Bright globular clusters in NGC 5128: the missing link between young massive clusters and evolved massive objects
• Dwarf-spheroidal satellites: are they of tidal origin?
• A discontinuity in the low-mass initial mass function
• Faint dwarf spheroidals in the Fornax Cluster: A flat luminosity function
• The Globular Cluster Luminosity Function: New Progress in Understanding an Old Distance Indicator
• Empirical Models for Dark Matter Halos. III. The Kormendy relation and the log(rho_e)-log(R_e) relation
• HST photometry of Globular Clusters in the Sombrero Galaxy
• UCD Candidates in the Hydra Cluster
• Search for Tidal Dwarf Galaxies Candidates in a Sample of Ultraluminous Infrared Galaxies
• Metallicity and age gradients in round elliptical galaxies
• Medium resolution spectroscopy in Omega Centauri: abundances of 400 subgiant and turn-off region
• Blue Straggler Stars in Galactic Open Clusters and the Simple Stellar Population Model
• Enhanced Mass-to-Light Ratios in UCDs through Tidal Interaction with the Centre of the Host Galaxy

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• The orbital poles of Milky Way satellite galaxies: a rotationally supported disc-of-satellites
• The Nature of UCDs: Internal Dynamics from an Expanded Sample and Homogeneous Database
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• Spatially Resolved Kinematics of an Ultra-Compact Dwarf Galaxy
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• The SLUGGS Survey: HST/ACS Mosaic Imaging of the NGC 3115 Globular Cluster System
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• J-PLUS: A wide-field multi-band study of the M15 globular cluster. Evidence of multiple stellar populations in the RGB
• Was the Milky Way a chain galaxy? Using the IGIMF theory to constrain the thin-disk star formation history and mass
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• The Lifetimes of Star Clusters Born with a Top-heavy IMF
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