scholarly journals MOCCA Survey Database: Extra Galactic Globular Clusters. I. Method and first results

2021 ◽  
Author(s):  
A Leveque ◽  
M Giersz ◽  
M Paolillo
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Velocity Dispersion ◽  
Structural Parameters ◽  
Dynamical Evolution ◽  
Central Surface ◽  
First Results ◽  
Preliminary Study ◽  
Galactic Globular Clusters ◽  
Gaia Dr2

Abstract Over the last few decades, exhaustive surveys of extra Galactic globular clusters (EGGCs) have become feasible. Only recently, limited kinematical information of globular clusters (GCs) were available through Gaia DR2 spectroscopy and also proper motions. On the other hand, simulations of GCs can provide detailed information about the dynamical evolution of the system. We present a preliminary study of EGGCs- properties for different dynamical evolutionary stages. We apply this study to 12 Gyr-old GCs simulated as part of the MOCCA Survey Database. Mimicking observational limits, we consider only a subssample of the models in the database, showing that it is possible to represent observed Milky Way GCs. In order to distinguish between different dynamical states of EGGCs, at least three structural parameters are necessary. The best distinction is achieved by considering the central parameters, those being observational core radius, central surface brightness, ratio between central and half-mass velocity dispersion, or similarly considering the central color, the central V magnitude and the ratio between central and half-mass radius velocity dispersion, although such properties could be prohibitive with current technologies. A similar but less solid result is obtained considering the average properties at the half-light radius, perhaps accessible presently in the Local Group. Additionally, we mention that the color spread in EGGCs due to internal dynamical models, at fixed metallcity, could be just as important due to the spread in metallicity.

scholarly journals The Structure of Collapsed Cluster Cores

1988 ◽  
Vol 126 ◽  
pp. 657-658
Author(s):  
Phyllis M. Lugger ◽  
Haldan Cohn ◽  
Jonathan E. Grindlay ◽  
Charles D. Bailyn ◽  
Paul Hertz
Keyword(s):  
Power Law ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Core Collapse ◽  
Central Surface ◽  
Core Profile ◽  
Galactic Globular Clusters ◽  
Cluster Cores

In order to test the prediction that many Galactic globular clusters have undergone core collapse (Lightman 1982, Cohn and Hut 1984) and should therefore have central surface brightness cusps, we have obtained UBVR CCD frames of the cores of 72 clusters. We present and analyze U-band surface brightness profiles for three clusters: one “control cluster” with a normal flat core profile — NGC 6388 — and two with central power law cusps — NGC 6624 and M15 (NGC 7078).

scholarly journals Galactic Globular Clusters: A new catalog of masses, structural parameters, velocity dispersion profiles, proper motions and space orbits

2019 ◽  
Vol 14 (S351) ◽  
pp. 451-454 ◽  
Author(s):  
Michael Hilker ◽  
Holger Baumgardt ◽  
Antonio Sollima ◽  
Andrea Bellini
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Structural Parameters ◽  
Large Set ◽  
Proper Motions ◽  
Density Profiles ◽  
Fundamental Parameters ◽  
Initial Cluster ◽  
Galactic Globular Clusters ◽  
Dependent Mass

AbstractWe collected radial velocities of more than 50.000 individual stars in 156 Galactic globular clusters (GGC) and matched them with HST photometry and Gaia DR2 proper motions. This allowed us to derive the GGC’s mean proper motions and space velocities. By fitting a large set of N-body simulations to their velocity dispersion and surface density profiles, combined with new measurements of their internal radially dependent mass functions, we have determined their present-day masses and structural parameters, and for 144 GGCs their internal kinematics. We also derive the initial cluster masses by calculating the cluster orbits backwards in time applying suitable recipes to account for mass-loss and dynamical friction. The new fundamental parameters of GGCs are publicly available via an online database, which will regularly be updated.

scholarly journals MOCCA survey database I: Preliminary mock Extra Galactic Globular Cluster observations

2019 ◽  
Vol 14 (S351) ◽  
pp. 122-125
Author(s):  
Agostino Leveque ◽  
Mirosław Giersz
Keyword(s):  
Spatial Distribution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Stellar Population ◽  
Dynamical Evolution ◽  
The Other ◽  
Population Synthesis ◽  
Stellar Population Synthesis ◽  
Preliminary Study

AbstractThe photometric properties that we could observe for Extra-Galactic Globular Clusters (EGGCs) are the integrated light of the system and for nearby EGGCs it also is possible to measure both half-light radii and the color spatial distribution, e.g. for areas smaller and larger than the half-light radius. No information about the internal dynamical state of the system could be directly obtained from observations. On the other hand, simulations of Globular Clusters (GCs) can provide detailed information about the dynamical evolution of the system.We present a preliminary study of EGGCs’ photometric properties for different dynamical evolutionary stages. We apply this study to 12Gyr old GCs simulated as part of the MOCCA Survey Database. We determine the magnitudes in different bands from their projected snapshots using the Flexible Stellar Population Synthesis (FSPS) code and we measure the half-light radii from the surface brightness.

scholarly journals Characterizing dynamical stages of open clusters located in the Sagittarius spiral arm

2019 ◽  
Vol 488 (2) ◽  
pp. 1635-1651 ◽  
Author(s):  
M S Angelo ◽  
A E Piatti ◽  
W S Dias ◽  
F F S Maia
Keyword(s):  
Structural Parameters ◽  
Three Dimensional ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Mass Star ◽  
Proper Motions ◽  
Concentration Parameter ◽  
Low Mass ◽  
Gaia Dr2 ◽  
Spiral Arm

Abstract The study of dynamical properties of Galactic open clusters (OCs) is a fundamental prerequisite for the comprehension of their dissolution processes. In this work, we characterized 12 OCs, namely: Collinder 258, NGC 6756, Czernik 37, NGC 5381, Ruprecht 111, Ruprecht 102, NGC 6249, Basel 5, Ruprecht 97, Trumpler 25, ESO 129−SC32, and BH 150, projected against dense stellar fields. In order to do that, we employed Washington CT1 photometry and Gaia DR2 astrometry, combined with a decontamination algorithm applied to the three-dimensional astrometric space of proper motions and parallaxes. From the derived membership likelihoods, we built decontaminated colour–magnitude diagrams, while structural parameters were obtained from King profiles fitting. Our analysis revealed that they are relatively young OCs (log(t  yr−1) ∼7.3–8.6), placed along the Sagittarius spiral arm, and at different internal dynamical stages. We found that the half-light radius to Jacobi radius ratio, the concentration parameter and the age to relaxation time ratio describe satisfactorily their different stages of dynamical evolution. Those relative more dynamically evolved OCs have apparently experienced more important low-mass star loss.

scholarly journals No evidence for intermediate-mass black holes in the globular clusters ω Cen and NGC 6624

2019 ◽  
Vol 488 (4) ◽  
pp. 5340-5351 ◽  
Author(s):  
H Baumgardt ◽  
C He ◽  
S M Sweet ◽  
M Drinkwater ◽  
A Sollima ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Velocity Dispersion ◽  
Stellar Mass ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Measured Velocity ◽  
Large Grid

ABSTRACT We compare the results of a large grid of N-body simulations with the surface brightness and velocity dispersion profiles of the globular clusters ω Cen and NGC 6624. Our models include clusters with varying stellar-mass black hole retention fractions and varying masses of a central intermediate-mass black hole (IMBH). We find that an $\sim 45\, 000$ M⊙ IMBH, whose presence has been suggested based on the measured velocity dispersion profile of ω Cen, predicts the existence of about 20 fast-moving, m > 0.5 M⊙, main-sequence stars with a (1D) velocity v > 60 km s−1 in the central 20 arcsec of ω Cen. However, no such star is present in the HST/ACS proper motion catalogue of Bellini et al. (2017), strongly ruling out the presence of a massive IMBH in the core of ω Cen. Instead, we find that all available data can be fitted by a model that contains 4.6 per cent of the mass of ω Cen in a centrally concentrated cluster of stellar-mass black holes. We show that this mass fraction in stellar-mass BHs is compatible with the predictions of stellar evolution models of massive stars. We also compare our grid of N-body simulations with NGC 6624, a cluster recently claimed to harbour a 20 000 M⊙ black hole based on timing observations of millisecond pulsars. However, we find that models with MIMBH > 1000 M⊙ IMBHs are incompatible with the observed velocity dispersion and surface brightness profile of NGC 6624, ruling out the presence of a massive IMBH in this cluster. Models without an IMBH provide again an excellent fit to NGC 6624.

scholarly journals Dynamical evolution of rotating globular clusters with embedded black holes

2006 ◽  
Vol 2 (S238) ◽  
pp. 363-364 ◽  
Author(s):  
José Fiestas ◽  
Rainer Spurzem
Keyword(s):  
Black Holes ◽  
Angular Momentum ◽  
Globular Clusters ◽  
Structural Parameters ◽  
Dynamical Evolution ◽  
Meridional Plane ◽  
Angular Momentum Transport ◽  
Dimensional Distribution ◽  
Velocity Diffusion ◽  
Parent Galaxy

AbstractEvolution of rotating globular clusters with embedded black holes is presented. The interplay between velocity diffusion due to relaxation and black hole star accretion is followed together with cluster rotation, using 2-dimensional, in energy and z-component of angular momentum, Fokker Planck numerical methods. Gravogyro and gravothermal instabilities drive the system to a faster evolution leading to shorter collapse times and a faster cluster dissolution in the tidal field of a parent galaxy.Angular momentum transport and star accretion support the development of central rotation in relaxation time scales. Two-dimensional distribution (in the meridional plane) of kinematical and structural parameters (density, dispersions, rotation) are reproduced, with the aim to enable the use of set of models for comparison with observational data.

scholarly journals G2C2 – III. Structural parameters for Galactic globular clusters in SDSS passbands

2015 ◽  
Vol 450 (3) ◽  
pp. 2692-2707 ◽  
Author(s):  
Joachim Vanderbeke ◽  
Roberto De Propris ◽  
Sven De Rijcke ◽  
Maarten Baes ◽  
Michael J. West ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Structural Parameters ◽  
Galactic Globular Clusters

scholarly journals Stellar-mass Black Holes in Globular Clusters: Dynamical consequences and observational signatures

2019 ◽  
Vol 14 (S351) ◽  
pp. 395-399 ◽  
Author(s):  
Abbas Askar ◽  
Mirek Giersz ◽  
Manuel Arca Sedda ◽  
Ammar Askar ◽  
Mario Pasquato ◽  
...  
Keyword(s):  
Black Holes ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Stellar Mass ◽  
Large Set ◽  
Term Survival ◽  
Central Surface ◽  
Sizeable Number ◽  
Hubble Time

AbstractSizeable number of stellar-mass black holes (BHs) in globular clusters (GCs) can strongly influence the dynamical evolution and observational properties of their host cluster. Using results from a large set of numerical simulations, we identify the key ingredients needed to sustain a sizeable population of BHs in GCs up to a Hubble time. We find that while BH natal kick prescriptions are essential in determining the initial retention fraction of BHs in GCs, the long-term survival of BHs is determined by the size, initial central density and half-mass relaxation time of the GC. Simulated GC models that contain many BHs are characterized by relatively low central surface brightness, large half-light and core radii values. We also discuss novel ways to compare simulated results with available observational data to identify GCs that are most likely to contain many BHs.

scholarly journals Improved dynamical modelling of the Arches cluster

2013 ◽  
Vol 9 (S303) ◽  
pp. 59-60
Author(s):  
Joowon Lee ◽  
Sungsoo S. Kim
Keyword(s):  
Surface Brightness ◽  
Massive Star ◽  
Velocity Dispersion ◽  
Galactic Center ◽  
Dynamical Evolution ◽  
Star Cluster ◽  
Initial Mass ◽  
Data Set ◽  
Cluster A ◽  
Best Fit

AbstractRecently, Clarkson et al. (2012) measured the intrinsic velocity dispersion of the Arches cluster, a young and massive star cluster in the Galactic center. Using the observed velocity dispersion profile and the surface brightness profile of Espinoza et al. (2009), they estimate the cluster's present-day mass to be ∼ 1.5×104 M⊙ by fitting an isothermal King model. In this study, we trace the best-fit initial mass for the Arches cluster using the same observed data set and also the anisotropic Fokker-Planck calculations for the dynamical evolution.

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