Properties of quasi-relaxed stellar systems in an external tidal field

Abstract

In a previous paper, we have constructed a family of self-consistent triaxial models of quasi-relaxed stellar systems, shaped by the tidal field of the hosting galaxy, as an extension of the well-known spherical King models. For a given tidal field, the models are characterized by two physical scales (such as total mass and central velocity dispersion) and two dimensionless parameters (the concentration parameter and the tidal strength). The most significant departure from spherical symmetry occurs when the truncation radius of the corresponding spherical King model is of the order of the tidal radius, which, for a given tidal strength, is set by the maximum concentration value admitted. For such maximally extended (or "critical") models the outer boundary has a generally triaxial shape, given by the zero-velocity surface of the relevant Jacobi integral, which is basically independent of the concentration parameter. In turn, the external tidal field can give rise to significant global departures from spherical symmetry (as measured, for example, by the quadrupole of the mass distribution of the stellar system) only for low-concentration models, for which the allowed maximal value of the tidal strength can be relatively high. In this paper we describe in detail the intrinsic and the projected structure and kinematics of the models, covering the entire parameter space, from the case of sub-critical (characterized by "underfilling" of the relevant Roche volume) to that of critical models. The intrinsic properties can be a useful starting point for numerical simulations and other investigations that require initialization of a stellar system in dynamical equilibrium. The projected properties are a key step in the direction of a comparison with observed globular clusters and other candidate stellar systems.

13 pages, 11 figures, uses emulateapj.cls with apjfonts.sty. Accepted for publication in The Astrophysical Journal

References in corpus (5)

• Lifetimes of tidally limited star clusters with different radii
• Effects of Primordial Mass Segregation on the Dynamical Evolution of Star Clusters
• The construction of non-spherical models of quasi-relaxed stellar systems
• The surprising external upturn of the Blue Straggler radial distribution in M55
• The Flattening of Globular Clusters

Cited by in corpus (11)

• A family of lowered isothermal models
• The ultra-diffuse galaxy NGC 1052-DF2 with MUSE: I. Kinematics of the stellar body
• Globular cluster number density profiles using Gaia DR2
• MIKiS: the Multi-Instrument Kinematic Survey of Galactic Globular Clusters. I. Velocity dispersion profiles and rotation signals of 11 globular clusters
• Star Clusters in Evolving Galaxies
• Self-consistent models of quasi-relaxed rotating stellar systems
• On the origin of intrinsic alignment in cosmic shear measurements: an analytic argument
• The longevity of the oldest open clusters: Structural parameters of NGC 188, NGC 2420, NGC 2425, NGC 2682, NGC 6791, NGC 6819
• Truncated $\gamma$-exponential models for tidal stellar systems
• Three candidate double clusters in the LMC: truth or dare?
• Merged or monolithic? Using machine-learning to reconstruct the dynamical history of simulated star clusters