Dissolution is the solution: on the reduced mass-to-light ratios of Galactic globular clusters

Abstract

The observed dynamical mass-to-light (M/L) ratios of globular clusters (GCs) are systematically lower than those expected from `canonical' simple stellar population models, which do not account for the preferential loss of low-mass stars due to energy equipartition. It was recently shown that low-mass star depletion can qualitatively explain the M/L discrepancy. To verify whether it is indeed the driving mechanism, we derive dissolution timescales and use these to predict the M/L_V ratios of the 24 Galactic GCs for which orbital parameters and dynamical M/L_V are known. We also predict the slopes of their low-mass stellar mass functions (MFs). We use the SPACE cluster models, which include dynamical dissolution, low-mass star depletion, stellar evolution, stellar remnants and various metallicities. The predicted M/L_V are in 1 sigma agreement with the observations for 12 out of 24 GCs. The discrepancy for the other GCs probably arises because our predictions give global M/L ratios, while the observations represent extrapolated central values that are different from global ones in case of mass segregation and a long dissolution timescale. GCs in our sample which likely have dissimilar global and central M/L ratios can be excluded by imposing limits on the dissolution timescale and King parameter. For the remaining GCs, the observed and predicted average M/L_V are 78^+9_-11% and 78+/-2% of the canonically expected values, while for the entire sample the values are 74^+6_-7% and 85+/-1%. The predicted correlation between the slope of the low-mass stellar MF and M/L_V is qualitatively consistent with observed MF slopes. It is concluded that the variation of M/L ratio due to dissolution and low-mass star depletion is a plausible explanation for the discrepancy between the observed and canonically expected M/L ratios of GCs. (Abridged)

17 pages, 10 figures, 6 tables; paper accepted for publication in A&A

References in corpus (18)

• Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
• The Initial-Final Mass Relation: Direct Constraints at the Low Mass End
• Star cluster disruption by giant molecular clouds
• From star clusters to dwarf galaxies: The properties of dynamically hot stellar systems
• The Nature of UCDs: Internal Dynamics from an Expanded Sample and Homogeneous Database
• Uniting Old Stellar Systems: From Globular Clusters to Giant Ellipticals
• Evidence for primordial mass segregation in globular clusters
• Why haven't loose globular clusters collapsed yet?
• Dynamical masses of ultra-compact dwarf galaxies in Fornax
• Bright globular clusters in NGC 5128: the missing link between young massive clusters and evolved massive objects
• The orbits of 48 globular clusters in a Milky-Way-Like Barred Galaxy
• High mass-to-light ratios of UCDs - Evidence for dark matter ?
• The photometric evolution of star clusters and the preferential loss of low-mass bodies - with an application to globular clusters
• Six New Galactic Orbits of Globular Clusters in a Milky-Way-Like Galaxy
• The Dynamical Effects of White Dwarf Birth Kicks in Globular Star Clusters
• Stellar Population Constraints on the Dark Matter Content and Origin of Ultra-Compact Dwarf Galaxies
• Explaining the mass-to-light ratios of globular clusters
• NGC2298: a globular cluster on its way to disruption

Cited by in corpus (73)

• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• Multiple Stellar Populations in Globular Clusters
• A catalogue of masses, structural parameters and velocity dispersion profiles of 112 Milky Way globular clusters
• The formation and assembly history of the Milky Way revealed by its globular cluster population
• Globular clusters as the relics of regular star formation in 'normal' high-redshift galaxies
• The E-MOSAICS Project: simulating the formation and co-evolution of galaxies and their star cluster populations
• Local-Group tests of dark-matter Concordance Cosmology: Towards a new paradigm for structure formation
• N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes
• Co-Evolution of Galactic Nuclei and Globular Cluster Systems
• The AIMSS Project I: Bridging the Star Cluster - Galaxy Divide
• Globular cluster formation in the context of galaxy formation and evolution
• Modeling the formation and evolution of star cluster populations in galaxy simulations
• The formation and hierarchical assembly of globular cluster populations
• Galactic Dark Matter Halos and Globular Cluster Populations. III: Extension to Extreme Environments
• The E-MOSAICS project: tracing galaxy formation and assembly with the age-metallicity distribution of globular clusters
• Connecting the first galaxies with ultra faint dwarfs in the Local Group: chemical signatures of Population~III stars
• Star Clusters in M31: V. Internal Dynamical Trends: Some Troublesome, Some Reassuring
• Measuring the mass of the central black hole in the bulgeless galaxy NGC 4395 from gas dynamical modeling
• Mass loss rates and the mass evolution of star clusters
• Limits on intermediate-mass black holes in six Galactic globular clusters with integral-field spectroscopy
• Halo globular clusters observed with AAOmega: dark matter content, metallicity and tidal heating
• Gas expulsion in massive star clusters? Constraints from observations of young and gas-free objects
• Measuring Consistent Masses for 25 Milky Way Globular Clusters
• On central black holes in ultra-compact dwarf galaxies
• Globular Cluster Mass Loss in the Context of Multiple Populations
• The Nuclear Cluster of the Milky Way: Total Mass and Luminosity (long version)
• The effect of feedback and reionization on star formation in low-mass dwarf galaxy haloes
• Synthetic catalog of black holes in the Milky Way
• Back to the Future: Estimating Initial Globular Cluster Masses from their Present Day Stellar Mass Functions
• Dynamical versus Stellar Masses of Ultracompact Dwarf Galaxies in the Fornax Cluster
• The evolution of the stellar mass function in star clusters
• Direct N-body simulations of globular clusters: (I) Palomar 14
• The Search for Multiple Populations in Magellanic Cloud Clusters III: No evidence for Multiple Populations in the SMC cluster NGC 419
• Two formation channels of UCDs in Hickson Compact Groups
• A comparison between the stellar and dynamical masses of six globular clusters
• Kinetic energy from supernova feedback in high-resolution galaxy simulations
• Testing Newtonian Gravity with AAOmega: Mass-To-Light Profiles and Metallicity Calibrations From 47 Tuc and M55
• Spatially Resolved Kinematics of an Ultra-Compact Dwarf Galaxy
• The origin of the 'blue tilt' of globular cluster populations in the E-MOSAICS simulations
• The impact of stripped Nuclei on the Super-Massive Black Hole number density in the local Universe
• N-body simulations of globular clusters in tidal fields: Effects of intermediate-mass black holes
• Characteristic radii of the Milky Way Globular Clusters
• An extended Pal 5 stream in Gaia DR2
• Dissecting the Colour-Magnitude Diagram: A Homogeneous Catalogue of Stellar Populations in Globular Clusters
• Quantifying the Universality of the Stellar Initial Mass Function in Old Star Clusters
• The mass fraction of halo stars contributed by the disruption of globular clusters in the E-MOSAICS simulations
• A Possible Solution for the $M/L-[Fe/H]$ Relation of Globular Clusters in M31. II. the Age-Metallicity Relation
• Evidence for Two Distinct Stellar Initial Mass Functions
• A Possible Solution for the M/L-[Fe/H] Relation of Globular Clusters in M31: A metallicity and density dependent top-heavy IMF
• The Optical Colors of Giant Elliptical Galaxies and their Metal-Rich Globular Clusters Indicate a Bottom-Heavy Initial Mass Function
• Did massive black holes in globular clusters initially satisfy galactic scaling relations?
• The Luminosity Function and stellar Mass to Light ratio of the massive globular cluster NGC2419
• The initial mass spectrum of old globular clusters in dwarf galaxies
• A systematic analysis of star cluster disruption by tidal shocks -- I. Controlled N-body simulations and a new theoretical model
• Searching in the dark: the dark mass content of the Milky Way globular clusters NGC288 and NGC6218
• Mass segregation in the outer halo globular cluster Palomar 14
• Star cluster dynamics
• The Effects of Dwarf Galaxies on the Orbital Evolution of Galactic Globular Clusters
• G2C2 - IV: A novel approach to study the radial distributions of multiple populations in Galactic globular clusters
• Globular clusters as a probe for Weyl Conformal Gravity
• MONDian dynamical modeling of NGC 288 with $\beta \ne 0$
• The Ophiuchus stream progenitor: a new type of globular cluster and its possible Sagittarius connection
• Evolution of the Mass and Luminosity Functions of Globular Star Clusters
• The Likelihood of Undiscovered Globular Clusters in the Outskirts of the Milky Way
• On the structure of Small Magellanic Cloud star clusters
• Dynamical Modeling of NGC 6809: Selecting the best model using Bayesian Inference
• A systematic analysis of star cluster disruption by tidal shocks -- II. Predicting star cluster dissolution rates from a time-series analysis of their tidal histories
• A new technique for the determination of the initial mass function in unresolved stellar populations
• On the Fundamental Line of Galactic and Extragalactic Globular Clusters
• The present-day globular cluster kinematics of lenticular galaxies from the E-MOSAICS simulations and their relation to the galaxy assembly histories
• Observational dynamics of low-mass stellar systems
• Made-to-Measure Modelling of Globular Clusters
• The dynamical evolution of the stellar clumps in the Sparkler galaxy