Searching for new observational signatures of the dynamical evolution of star clusters

Abstract

We present a numerical study, based on Monte Carlo simulations, aimed at defining new empirical parameters measurable from observations and able to trace the different phases of star cluster dynamical evolution. As expected, a central density cusp, deviating from the King model profile, develops during the core collapse (CC) event. Although the slope varies during the post-CC oscillations, the cusp remains a stable feature characterizing the central portion of the density profile in all post-CC stages. We then investigate the normalized cumulative radial distribution (nCRD) drawn by all the cluster stars included within one half the tridimensional half-mass radius (R<0.5 rh), finding that its morphology varies in time according to the cluster's dynamical stage. To quantify these changes we defined three parameters: A5, the area subtended by the nCRD within 5% of the half-mass radius, P5, the value of the nCRD measured at the same distance, and S2.5, the slope of the straight line tangent to the nCRD measured at R=2.5% rh. The three parameters evolve similarly during the cluster's dynamical evolution: after an early phase in which they are essentially constant, their values rapidly increase, reaching their maximum at the CC epoch and slightly decreasing in the post-CC phase, when their average value remains significantly larger than the initial one, in spite of some fluctuations. The results presented in the paper suggest that these three observable parameters are very promising empirical tools to identify the star cluster's dynamical stage from observational data.

arXiv comment18 pages, 11 figures, accepted for publication in ApJ

References in corpus (47)

• On the variation of the Initial Mass Function
• Evolution of binary stars and the effect of tides on binary populations
• Comprehensive analytic formulae for stellar evolution as a function of mass and metallicity
• A statistical study of 233 pulsar proper motions
• Dynamical evolution of star clusters in tidal fields
• The ACS Survey of Galactic Globular Clusters. VII. Relative Ages
• Internal Dynamics of Globular Clusters
• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• Dynamical Formation of Close Binary Systems in Globular Clusters
• Twenty-One Millisecond Pulsars in Terzan 5 Using the Green Bank Telescope
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• Modeling Dense Star Clusters in the Milky Way and Beyond with the $\text{CMC}$ Cluster Catalog
• Accreted versus In Situ Milky Way Globular Clusters
• Two distinct sequences of blue straggler stars in the globular cluster M30
• MOCCA Code for Star Cluster Simulations - II. Comparison with N-body Simulations
• MOCCA code for star cluster simulations - I. Blue Stragglers, first results
• Star count density profiles and structural parameters of 26 Galactic globular clusters
• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• New density profile and structural parameters of the complex stellar system Terzan 5
• Monte Carlo Simulations of Globular Cluster Evolution. V. Binary Stellar Evolution
• Double Blue Straggler sequences in GCs: the case of NGC 362
• Blue Stragglers as Stellar Collision Products: the Angular Momentum Question
• A novel look at energy equipartition in globular clusters
• ON BLUE STRAGGLER FORMATION BY DIRECT COLLISIONS OF MAIN-SEQUENCE STARS
• Star Clusters with Primordial Binaries: I. Dynamical Evolution of Isolated Models
• The puzzling dynamical status of the core of the globular cluster NGC 6752
• Hubble Space Telescope Proper motion (HSTPROMO) Catalogs of Galactic Globular Clusters. VI. Improved data reduction and internal-kinematic analysis of NGC 362
• The surface density profile of NGC 6388: a good candidate for harboring an intermediate-mass black hole
• Tidal disruption, global mass function and structural parameters evolution in star clusters
• Star Clusters with Primordial Binaries: II. Dynamical Evolution of Models in a Tidal Field
• Investigating mass segregation process in globular clusters with Blue Straggler Stars: the impact of dark remnants
• A Panchromatic Study of the Globular Cluster NGC 1904. I: The Blue Straggler Population
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - XV. The dynamical clock: reading cluster dynamical evolution from the segregation level of blue straggler stars
• Blue Straggler masses from pulsation properties. I. The case of NGC6541
• A supra-massive population of stellar-mass black holes in the globular cluster Palomar 5
• White Dwarf Subsystems in Core-Collapsed Globular Clusters
• MOCCA Survey Database I: Dissolution of tidally filling star clusters harbouring BH subsystems
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XVIII. Proper-motion kinematics of multiple stellar populations in the core regions of NGC 6352
• Kinematical evolution of tidally limited star clusters: the role of retrograde stellar orbits
• The "dynamical clock": dating the internal dynamical evolution of star clusters with Blue Straggler Stars
• On the Link Between Energy Equipartition and Radial Variation in the Stellar Mass Function of Star Clusters
• Star density profiles of six old star clusters in the Large Magellanic Cloud
• Discovery of a double Blue Straggler sequence in M15: new insight into the core-collapse process
• Kinematic fingerprint of core-collapsed globular clusters
• Spectral Energy Distribution of Blue Stragglers in the core of 47 Tucanae
• The origin of the two populations of blue stragglers in M30
• Structure and Internal Kinematics of Nine Inner Milky Way Globular Clusters

Cited by in corpus (5)

• Discovery of a double sequence of blue straggler stars in the core-collapsed globular cluster NGC 6256
• Digging into the Galactic Bulge: stellar population and structure of the poorly studied cluster NGC 6316
• Empirical measurement of the dynamical ages of three globular clusters and some considerations on the use of the dynamical clock
• Internal kinematics and structure of the bulge globular cluster NGC 6569
• A Photometric in-depth look at the core-collapsed globular cluster NGC 6284