The Structural and Kinematic Evolution of Central Star Clusters in Dwarf Galaxies and Their Dependence on Dark Matter Halo Profiles

Abstract

Through a suite of direct N-body simulations, we explore how the structural and kinematic evolution of a star cluster located at the center of a dwarf galaxy is affected by the shape of its host's dark matter density profile. The stronger central tidal fields of cuspier halos minimize the cluster's ability to expand in response to mass loss due to stellar evolution during its early evolutionary stages and during its subsequent long-term evolution driven by two-body relaxation. Hence clusters evolving in cuspier dark matter halos are characterized by more compact sizes, higher velocity dispersions and remain approximately isotropic at all clustercentric distances. Conversely, clusters in cored halos can expand more and develop a velocity distribution profile that becomes increasingly radially anisotropic at larger clustercentric distances. Finally, the larger velocity dispersion of clusters evolving in cuspier dark matter profiles results in them having longer relaxation times. Hence clusters in cuspy galaxies relax at a slower rate and, consequently, they are both less mass segregated and farther from complete energy equipartition than cluster's in cored galaxies. Application of this work to observations allows for star clusters to be used as tools to measure the distribution of dark matter in dwarf galaxies and to distinguish isolated star clusters from ultra-faint dwarf galaxies.

8 pages, 7 figures, Accepted for publication in MNRAS

References in corpus (18)

• High-resolution mass models of dwarf galaxies from LITTLE THINGS
• The kinematic status and mass content of the Sculptor dwarf spheroidal galaxy
• The shape of the inner Milky Way halo from observations of the Pal 5 and GD-1 stellar streams
• Farthest Neighbor: The Distant Milky Way Satellite Eridanus II
• Globular Cluster Formation and Evolution in the Context of Cosmological Galaxy Assembly: Open Questions
• Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas Kinematics
• Milky Way Mass and Potential Recovery Using Tidal Streams in a Realistic Halo
• The core-cusp problem: a matter of perspective
• Evidence of a non universal stellar Initial Mass Function. Insights from HST optical imaging of 6 Ultra Faint Dwarf Milky Way Satellites
• Star Clusters in Evolving Galaxies
• Low EUV Luminosities Impinging on Protoplanetary Disks
• On the nature of ultra-faint dwarf galaxy candidates I: DES1, Eridanus III and Tucana V
• Deadly dark matter cusps vs faint and extended star clusters: Eridanus II and Andromeda XXV
• Modeling the gravitational potential of a cosmological dark matter halo with stellar streams
• Bayesian Mass Estimates of the Milky Way: including measurement uncertainties with hierarchical Bayes
• On the Link Between Energy Equipartition and Radial Variation in the Stellar Mass Function of Star Clusters
• Radial Variation in the Stellar Mass Functions of Star Clusters
• Kinematic fingerprint of core-collapsed globular clusters

Cited by in corpus (7)

• Dark matters on the scale of galaxies
• Clearing the hurdle: The mass of globular cluster systems as a function of host galaxy mass
• The Quintuplet Cluster: Extended Structure and Tidal Radius
• Photometric and Kinematic study of the three intermediate age open clusters NGC 381, NGC 2360, and Berkeley 68
• The survival of globular clusters in a cuspy Fornax
• Globular clusters as probes of dark matter cusp-core transformations
• The proper motion of stars in dwarf galaxies: distinguishing central density cusps from cores