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Journal articles on the topic 'Globular Clusters Core Dynamics'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 February 2022

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1

Cohn, Haldan. "After Core Collapse. What?" Symposium - International Astronomical Union 126 (1988): 379–92. http://dx.doi.org/10.1017/s0074180900042613.

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As our understanding of core collapse in globular clusters has improved through detailed computer simulations, attention has naturally turned to dynamical evolution of globular clusters after core collapse. The results of recent simulations of post-collapse cluster evolution are reviewed. An assessment is given of progress towards the goal of developing astrophysically realistic models that cover all phases of globular cluster evolution. A focus of this review is the stability of the post-collapse expansion phase to the large amplitude core oscillations first observed in the simulations of Sug

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Ivanova, Natalia, and Frederic A. Rasio. "Compact Binaries in Globular Clusters." International Astronomical Union Colloquium 194 (2004): 67–70. http://dx.doi.org/10.1017/s0252921100151942.

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AbstractIn dense stellar systems the frequent dynamical interactions between stars play a crucial role in the formation and evolution of compact binaries. We study these processes using a novel approach combining a state-of-the- art binary population synthesis code with a simple treatment of dynamical interactions in dense star cluster cores. Here we focus on the dynamical and evolutionary processes leading to the formation of compact binaries containing white dwarfs in dense globular clusters. We demonstrate that dynamics can increase by factors ~ 2 – 100 the production rates of interesting b

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3

King, Ivan R. "Dynamical Implications of Deep HST Imaging of Globular Clusters." Symposium - International Astronomical Union 174 (1996): 29–38. http://dx.doi.org/10.1017/s0074180900001352.

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HST observations contribute in many ways to a better understanding of the dynamical nature of globular clusters. Unprecedentedly faint photometry gives new determinations of the numbers of low-mass stars. Cluster-to-cluster differences at the faint ends of the mass functions suggest differences in dynamical evolution. Mass segregation is clearly observed, from the envelope inward to the dense cluster center. The distribution of stars in the hitherto unresolved cores gives new data with which to test theories of core collapse, and these core profiles are also sensitive to the number of unseen r

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Piatti, Andrés E., Jeremy J. Webb, and Raymond G. Carlberg. "Characteristic radii of the Milky Way globular clusters." Monthly Notices of the Royal Astronomical Society 489, no. 3 (2019): 4367–77. http://dx.doi.org/10.1093/mnras/stz2499.

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ABSTRACT We report on the extent of the effects of the Milky Way gravitational field in shaping the structural parameters and internal dynamics of its globular cluster population. We make use of a homogeneous, up-to-date data set with kinematics, structural properties, current and initial masses of 156 globular clusters. In general, cluster radii increase as the Milky Way potential weakens; with the core and Jacobi radii being those which increase at the slowest and fastest rate, respectively. We interpret this result as the innermost regions of globular clusters being less sensitive to change

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Orkney, M. D. A., J. I. Read, J. A. Petts, and M. Gieles. "Globular clusters as probes of dark matter cusp-core transformations." Monthly Notices of the Royal Astronomical Society 488, no. 3 (2019): 2977–88. http://dx.doi.org/10.1093/mnras/stz1625.

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Abstract Bursty star formation in dwarf galaxies can slowly transform a steep dark matter cusp into a constant density core. We explore the possibility that globular clusters (GCs) retain a dynamical memory of this transformation. To test this, we use the nbody6df code to simulate the dynamical evolution of GCs, including stellar evolution, orbiting in static and time-varying potentials for a Hubble time. We find that GCs orbiting within a cored dark matter halo, or within a halo that has undergone a cusp-core transformation, grow to a size that is substantially larger (Reff &gt; 10 pc) th

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Sugimoto, Daiichiro. "A Comparative Study of Globular Clusters." Symposium - International Astronomical Union 174 (1996): 1–7. http://dx.doi.org/10.1017/s0074180900001327.

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This paper is intended for an introduction to the Symposium. In 47 Tuc many milli-second pulsars are found while none has been reported in ω Cen. One might think that in 47 Tuc they have been formed in the collapsed core through tidal capture of a main sequence star by a neutron star. If we use the standard model of gravothermal collapse of globular clusters to integrate the squared stellar density over the core and over its time history, we find, however, the accumulated probability of tidal capture is lower in 47 Tuc than ω Cen. Such contradiction suggests that it will be important to take a

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Noyola, Eva, Karl Gebhardt та Marcel Bergmann. "Central Dynamics of Globular Clusters: the Case for a Black Hole in ω Centauri". Proceedings of the International Astronomical Union 3, S246 (2007): 341–45. http://dx.doi.org/10.1017/s1743921308015895.

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AbstractThe globular cluster ω Centauri is one of the largest and most massive members of the Galactic system. Its classification as a globular cluster has been challenged making it a candidate for being the stripped core of an accreted dwarf galaxy; this and the fact that it has one of the largest velocity dispersions for star clusters in our galaxy makes it an interesting candidate for harboring an intermediate mass black hole. We measure the surface brightness profile from integrated light on an HST/ACS image, and find a central power-law cusp of logarithmic slope -0.08. We also analyze Gem

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Meylan, G., P. Dubath, and M. Mayor. "Dynamical study of the LMC globular cluster NGC 1978 from core velocity dispersion." Symposium - International Astronomical Union 148 (1991): 211–12. http://dx.doi.org/10.1017/s0074180900200405.

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The projected velocity dispersion in the core of the Large Magellanic Cloud (LMC) intermediate-age globular cluster NGC 1978 is deduced from integrated light spectra. A numerical cross-correlation technique gives a projected velocity dispersion σp(core) = 5.8±1.2 km s−1. Multimass anisotropic King-Michie dynamical models are applied to the observational constraints given by the surface brightness profile and the above central projected velocity dispersion. Depending on the model, the values obtained for the total mass of the cluster range from 0.36 to 1.44 106M⊙, corresponding to mass-to-light

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Kremer, Kyle, Claire S. Ye, Sourav Chatterjee, Carl L. Rodriguez, and Frederic A. Rasio. "The Role of “black hole burning” in the evolution of dense star clusters." Proceedings of the International Astronomical Union 14, S351 (2019): 357–66. http://dx.doi.org/10.1017/s1743921319007269.

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AbstractAs self-gravitating systems, dense star clusters exhibit a natural diffusion of energy from their innermost to outermost regions, leading to a slow and steady contraction of the core until it ultimately collapses under gravity. However, in spite of the natural tendency toward “core collapse,” the globular clusters (GCs) in the Milky Way exhibit a well-observed bimodal distribution in core radii separating the core-collapsed and non-core-collapsed clusters. This suggests an internal energy source is at work, delaying the onset of core collapse in many clusters. Over the past decade, a l

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Belloni, Diogo, Mirek Giersz, Liliana E. Rivera Sandoval, Abbas Askar, and Pawel Ciecielag. "Are most Cataclysmic Variables in Globular Clusters dynamically formed?" Proceedings of the International Astronomical Union 14, S351 (2019): 404–7. http://dx.doi.org/10.1017/s174392131900718x.

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AbstractWe have been investigating populations of cataclysmic variables (CVs) in a set of more than 300 globular cluster (GC) models evolved with themoccacode.[-120pt] One of the main questions we have intended to answer is whether most CVs in GCs are dynamically formed or not. Contrary to what has been argued for a long time, we found that dynamical destruction of primordial CV progenitors is much stronger in GCs than dynamical formation of CVs. In particular, we found that, on average, the detectable CV population is predominantly composed of CVs formed via a typical common envelope phase (≳

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Vaidya, Kaushar, Khushboo K. Rao, Manan Agarwal, and Souradeep Bhattacharya. "Blue straggler populations of seven open clusters with Gaia DR2." Monthly Notices of the Royal Astronomical Society 496, no. 2 (2020): 2402–21. http://dx.doi.org/10.1093/mnras/staa1667.

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ABSTRACT Blue straggler stars (BSS) are well studied in globular clusters but their systematic study with secure membership determination is lacking in open clusters. We use Gaia DR2 data to determine accurate stellar membership for four intermediate-age open clusters, namely Melotte 66, NGC 2158, NGC 2506, and NGC 6819, and three old open clusters, namely, Berkeley 39, NGC 188, and NGC 6791, to subsequently study their BSS populations. The BSS radial distributions of five clusters, namely Melotte 66, NGC 188, NGC 2158, NGC 2506, and NGC 6791, show bimodal distributions, placing them with Fami

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Kumamoto, Jun, Michiko S. Fujii, and Ataru Tanikawa. "Unexpectedly high formation rate of merging binary black holes in open clusters." Proceedings of the International Astronomical Union 14, S351 (2019): 204–7. http://dx.doi.org/10.1017/s1743921319007129.

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AbstractGravitational wave direct detections suggest that 30 M⊙ binary black holes (BBHs) commonly exist in the universe. One possible formation scenario of such BBHs is dynamical three-body encounters in dense star clusters. We performed a series of direct N-body simulations with a mass of 2500 and 10000 M⊙ and found a new channel for the formation of BBHs which is dominant in open clusters. In open clusters, the core-collapse time is shorter than in globular clusters, and therefore massive main-sequence (MS) binaries can form before they evolve to BHs. These MS binaries experience common env

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Ostriker, Jeremiah P. "The Evolution of the System of Globular Clusters." Symposium - International Astronomical Union 126 (1988): 271–81. http://dx.doi.org/10.1017/s0074180900042534.

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Globular clusters have a sufficiently distinct character that we can treat the system of globular clusters, as a distinct object which has a size, mass and angular momentum, but also, an internal density distribution, velocity distribution, and, in general, a detailed interior structure. Shapley, of course, pioneered in the effort to model, that is to describe, the existing state of the system from our vantage point. At the present time we probably have an inventory of clusters which is largely complete, and for the majority of the identified systems we have good knowledge (cf for example Webb

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Meadows, Noah, Julio F. Navarro, Isabel Santos-Santos, Alejandro Benítez-Llambay, and Carlos Frenk. "Cusp or core? Revisiting the globular cluster timing problem in Fornax." Monthly Notices of the Royal Astronomical Society 491, no. 3 (2019): 3336–42. http://dx.doi.org/10.1093/mnras/stz3280.

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ABSTRACT We use N-body simulations to revisit the globular cluster (GC) ‘timing problem’ in the Fornax dwarf spheroidal (dSph). In agreement with earlier work, we find that, due to dynamical friction, GCs sink to the centre of dark matter haloes with a cuspy inner density profile but ‘stall’ at roughly 1/3 of the core radius (rcore) in haloes with constant-density cores. The time-scales to sink or stall depend strongly on the mass of the GC and on the initial orbital radius, but are essentially the same for either cuspy (Navarro–Frenk–White) or cored haloes normalized to have the same total ma

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Antonini, Fabio, and Mark Gieles. "Population synthesis of black hole binary mergers from star clusters." Monthly Notices of the Royal Astronomical Society 492, no. 2 (2020): 2936–54. http://dx.doi.org/10.1093/mnras/stz3584.

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ABSTRACT Black hole (BH) binary mergers formed through dynamical interactions in dense star clusters are believed to be one of the main sources of gravitational waves (GWs) for Advanced LIGO and Virgo. Here, we present a fast numerical method for simulating the evolution of star clusters with BHs, including a model for the dynamical formation and merger of BH binaries. Our method is based on Hénon’s principle of balanced evolution, according to which the flow of energy within a cluster must be balanced by the energy production inside its core. Because the heat production in the core is powered

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Decressin, Thibault. "Massive stars in globular clusters: drivers of chemical and dynamical evolution." Proceedings of the International Astronomical Union 6, S272 (2010): 227–32. http://dx.doi.org/10.1017/s1743921311010465.

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AbstractMassive stars have a strong impact on globular cluster evolution. First providing they rotate initially fast enough they can reach the break-up velocity during the main sequence and a mechanical mass-loss will eject matter from the equator at low velocity. Rotation-induced mixing will also bring matter from the convective core to the surface. From this ejected matter loaded in H-burning material a second generation of stars will born. The chemical pattern of these second generation stars are similar to the one observed for stars in globular cluster with abundance anomalies in light ele

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17

Richer, Harvey B. "The dynamical effect of white dwarf kicks in star clusters." Proceedings of the International Astronomical Union 5, S266 (2009): 318–19. http://dx.doi.org/10.1017/s1743921309991190.

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AbstractGlobular star clusters generally have large cores, i.e., rc/rh (the ratio of core to half-light radii) exceeds 0.3 for more than 50% of the Galactic globular clusters. In the absence of a central heating source, dynamical models suggest that massive clusters will contract, typically on a timescale shorter than a Hubble time, and exhibit a compact core. To explain the disagreement between observations and theory, intermediate-mass mass black holes have been invoked to explain the core structure. Recent observations, however, have failed to definitively prove their existence in clusters.

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Grindlay, Jonathan E. "High Resolution Studies of Compact Binaries in Globular Clusters With HST and ROSAT." Symposium - International Astronomical Union 174 (1996): 171–80. http://dx.doi.org/10.1017/s0074180900001509.

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The studies of compact binaries containing an accreting white dwarf or neutron star in the dense cores of globular clusters have made considerable progress in the past few years as a result of the high resolution images obtained with HST and ROSAT. It is now clear that cluster cores contain a significant population of these systems which must constrain the similarly large populations of millisecond pulsars as well as dynamical histories of clusters. The population of dim x-ray sources appears to be dominated by cataclysmic variables (CVs) formed by tidal capture and not exchange collisions. Ou

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Hilker, Michael. "Stellar population properties of the most massive globular clusters and ultra-compact dwarf galaxies of the Fornax cluster." Proceedings of the International Astronomical Union 12, S316 (2015): 99–104. http://dx.doi.org/10.1017/s1743921315009126.

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AbstractMost ultra-compact dwarf galaxies (UCDs) and very massive globular clusters reside in nearby galaxy clusters or around nearby giant galaxies. Due to their distance (> 4 Mpc) and compactness (reff < 100 pc) they are barely resolved, and thus it is difficult to obtain their internal properties. Here I present our most recent attempts to constrain the mass function, stellar content and dynamical state of UCDs in the Fornax cluster. Thanks to radial velocity membership assignment of ~ 950 globular clusters (GCs) and UCDs in the core of Fornax, the shape of their mass function is well

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Moretti, Alessia, Francesca De Angeli, and Giampaolo Piotto. "Environmental Effects on the Globular Cluster Blue Straggler Population: a Statistical Approach." Proceedings of the International Astronomical Union 3, S246 (2007): 369–70. http://dx.doi.org/10.1017/s1743921308015986.

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AbstractBlue stragglers stars (BSS) constitute an ubiquitous population of objects whose origin involves both dynamical and stellar evolution. We took advantage of the homogeneous sample of 56 Galactic globular clusters observed with WFPC2/HST by Piotto et al. (2002) to investigate the environmental dependence of the BSS formation mechanisms. We explore possible monovariate relations between the frequency of BSS (divided in different subsamples according to their location with respect to the parent cluster core radius and half mass radius) and the main parameters of their host GC. We also perf

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Larsen, Søren S., Jean P. Brodie, Bruce G. Elmegreen, Yuri N. Efremov, Paul W. Hodge, and Tom Richtler. "HST and Keck Observations of a Young Globular Cluster in the Spiral Galaxy NGC 6946." Symposium - International Astronomical Union 207 (2002): 700–702. http://dx.doi.org/10.1017/s0074180900224595.

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Using new (Cycle 9) HST / WFPC2 data, we have studied a peculiar star forming region in the nearby Sc-type spiral NGC 6946. The region has a bubble-like shape and a diameter of about 600 pc. Near the centre is an extremely luminous young globular cluster with MV = −13.2 mag. The cluster has a compact core with a core radius of about 1.3 pc but is surrounded by an extended halo with a power-law luminosity profile similar to that observed for young LMC clusters. From Keck / HIRES high-dispersion spectroscopy we measure a velocity dispersion of 10 km s−1, leading to a dynamical mass estimate of a

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Ryabova, Marina V., Alena S. Gorban, Yuri A. Shchekinov, and Evgenii O. Vasiliev. "Features of globular cluster’s dynamics with an intermediate-mass black hole." Open Astronomy 27, no. 1 (2018): 1–6. http://dx.doi.org/10.1515/astro-2018-0001.

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Abstract In this paper, we address the question of how a central intermediate-mass black hole (IMBH) in a globular cluster (GC) affects dynamics, core collapse, and formation of the binary population. It is shown that the central IMBH forms a binary system that affects dynamics of stars in the cluster significantly. The presence of an intermediate-mass black hole with mass ≥ 1.0-1.7%of the total stellar mass in the cluster inhibits the formation of binary stars population.

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Zaggia, S. R., G. Piotto, and M. Capaccioli. "Mapping the Stellar Distribution in Globular Clusters: An Application to NGC 6809 = M55." Symposium - International Astronomical Union 164 (1995): 409. http://dx.doi.org/10.1017/s007418090010926x.

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The principal aim of this work is to map the stellar distribution of a large sample of galactic globular clusters from the central regions to the outer envelope (beyond the tidal radius for an estimate of the foreground/background contamination) with a good statistical sampling of stars in the different branches of the color-magnitude diagram and with different masses. These new data will be used to investigate the dynamical evolution of stellar systems embedded in the gravitational field of our Galaxy, and, eventually, to set constraints on the mass distribution of the Milky Way. In this cont

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Decressin, T., H. Baumgardt, P. Kroupa, G. Meynet, and C. Charbonnel. "The ages of Galactic globular clusters in the context of self-enrichment." Proceedings of the International Astronomical Union 4, S258 (2008): 265–74. http://dx.doi.org/10.1017/s1743921309031913.

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AbstractA significant fraction of stars in globular clusters (about 70%-85%) exhibit peculiar chemical patterns, with strong abundance variations in light elements along with constant abundances in heavy elements. These abundance anomalies can be created in the H-burning core of a first generation of fast-rotating massive stars, and the corresponding elements are conveyed to the stellar surface thanks to rotational induced mixing. If the rotation of the stars is fast enough, this material is ejected at low velocity through a mechanical wind at the equator. It then pollutes the interstellar med

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Askar, Abbas, Mirek Giersz, Manuel Arca Sedda, Ammar Askar, Mario Pasquato, and Agostino Leveque. "Stellar-mass Black Holes in Globular Clusters: Dynamical consequences and observational signatures." Proceedings of the International Astronomical Union 14, S351 (2019): 395–99. http://dx.doi.org/10.1017/s1743921319006847.

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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. Simulate

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Da Costa, G. S., and K. C. Freeman. "The Dynamics of 47 Tucanae." Symposium - International Astronomical Union 113 (1985): 69–72. http://dx.doi.org/10.1017/s0074180900147230.

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Observations made at Las Campanas Observatory and at the Anglo-Australian Observatory have been used to determine line-of-sight velocities with an average accuracy of 3 kms−1 for 135 member stars in the globular cluster 47 Tucanae. The velocities were derived from cross-correlation techniques applied to 30 A/mm spectra obtained with digital sky-subtracting detectors. The spectra themselves have been used to analyze the cyanogen anomalies on the red giant branch in this cluster (Norris et al., 1984). When combined with the velocities published by the CORAVEL group (Mayor et al., 1983), these ob

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Shao, Shi, Marius Cautun, Carlos S. Frenk, et al. "The survival of globular clusters in a cuspy Fornax." Monthly Notices of the Royal Astronomical Society 507, no. 2 (2021): 2339–53. http://dx.doi.org/10.1093/mnras/stab2285.

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ABSTRACT It has long been argued that the globular clusters (GCs) in the Fornax dwarf galaxy indicate that its dark matter halo is likely to have a shallow density profile with a core of size ∼1 kpc. We revisit this argument by investigating analogues of Fornax formed in MOdelling Star cluster population Assembly In Cosmological Simulations within eagle (E-MOSAICS), a cosmological hydrodynamical simulation that follows the formation and evolution of GCs in the Evolution and Assembly of GaLaxies and their Environments (EAGLE) galaxy formation model. In eagle, Fornax-mass haloes are cuspy and we

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Shara, Michael M., Michael Potter, Anthony F. J. Moffat, Helen Sawyer Hogg, and Amelia Wehlau. "A Candidate for the Recovered Nova of 1938 in the Globular Cluster M 14." Symposium - International Astronomical Union 126 (1988): 585–86. http://dx.doi.org/10.1017/s0074180900043199.

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Although close binaries are believed to be of importance in the dynamical evolution of globular clusters, searches for such binaries have produced mostly negative results, aside from x-ray sources. Two dwarf novae which are possible cluster members are known (Margon and Downes 1983) and two classical nova candidates have been found. The crowded field around the nova observed in 1860 close to the center of M80 makes ground-based recovery of that star impossible with present techniques. Here we report on our attempt to recover the star which erupted in 1938 about 30″ (0.8 core radii) from the ce

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Samra, Raminder S., Harvey B. Richer, Jeremy S. Heyl, et al. "PROPER MOTIONS AND INTERNAL DYNAMICS IN THE CORE OF THE GLOBULAR CLUSTER M71." Astrophysical Journal 751, no. 1 (2012): L12. http://dx.doi.org/10.1088/2041-8205/751/1/l12.

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Prinja, Raman K., and Danielle Fenech. "The e-MERLIN Cyg OB2 radio survey (COBRaS)." Proceedings of the International Astronomical Union 6, S272 (2010): 306–7. http://dx.doi.org/10.1017/s1743921311010696.

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AbstractThe e-MERLIN Cyg OB2 Radio Survey (COBRaS) is designed to exploit e-MERLIN's enhanced capabilities to conduct uniquely probing, targeted deep-field mapping of the massive Cyg OB2 association in our Galaxy. The project aims to deliver (between 2010 to 2013) the most detailed radio census for the most massive OB association in the northern hemisphere, offering direct comparison to not only massive clusters in general, but also young globular clusters and super star clusters. With the COBRaS Legacy project we will assemble a uniform dataset of lasting value that is critical for advancing

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Wang, Long, Rainer Spurzem, Sverre Aarseth, et al. "Acceleration of hybrid MPI parallel NBODY6++ for large N-body globular cluster simulations." Proceedings of the International Astronomical Union 10, S312 (2014): 260–61. http://dx.doi.org/10.1017/s174392131500798x.

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AbstractPrevious research on globular clusters (GCs) dynamics is mostly based on semi-analytic, Fokker-Planck, Monte-Carlo methods and on direct N-body (NB) simulations. These works have great advantages but also limits since GCs are massive and compact and close encounters and binaries play very important roles in their dynamics. The former three methods make approximations and assumptions, while expensive computing time and number of stars limit the latter method. The current largest direct NB simulation has ~ 500k stars (Heggie 2014). Here, we accelerate the direct NB code NBODY6++ (which e

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Cuevas-Otahola, B., Y. D. Mayya, I. Puerari, and D. Rosa-González. "Mass–radius relation of intermediate-age disc super star clusters of M82." Monthly Notices of the Royal Astronomical Society 500, no. 4 (2020): 4422–38. http://dx.doi.org/10.1093/mnras/staa3513.

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ABSTRACT We present a complete set of structural parameters for a sample of 99 intermediate-age super star cluster (SSCs) in the disc of M82, and carry out a survival analysis using the semi-analytical cluster evolution code emacss. The parameters are based on the profile-fitting analysis carried out in previous work, with the mass-related quantities derived using a mass-to-light ratio for a constant age of 100 Myr. The SSCs follow a power-law mass function with an index α = 1.5, and a lognormal size function with a typical half-light radius, Rh = 4.3 pc, which is both comparable with the valu

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Giesers, Benjamin, Sebastian Kamann, Stefan Dreizler, et al. "A stellar census in globular clusters with MUSE: Binaries in NGC 3201." Astronomy & Astrophysics 632 (November 21, 2019): A3. http://dx.doi.org/10.1051/0004-6361/201936203.

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We utilise multi-epoch MUSE spectroscopy to study binary stars in the core of the Galactic globular cluster NGC 3201. Our sample consists of 3553 stars with 54 883 spectra in total comprising 3200 main-sequence stars up to 4 magnitudes below the turn-off. Each star in our sample has between 3 and 63 (with a median of 14) reliable radial velocity measurements within five years of observations. We introduce a statistical method to determine the probability of a star showing radial velocity variations based on the whole inhomogeneous radial velocity sample. Using HST photometry and an advanced dy

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Ye, Claire S., Kyle Kremer, Sourav Chatterjee, Carl L. Rodriguez, and Frederic A. Rasio. "Modeling Pulsars in dense star clusters." Proceedings of the International Astronomical Union 14, S351 (2019): 549–52. http://dx.doi.org/10.1017/s174392131900677x.

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AbstractOver a hundred millisecond radio pulsars (MSPs) have been observed in globular clusters (GCs), motivating theoretical studies of the formation and evolution of these sources through stellar evolution coupled to stellar dynamics. Here we study MSPs in GCs using realistic N-body simulations with our Cluster Monte Carlo code. We show that neutron stars (NSs) formed in electron-capture supernovae can be spun up through mass transfer to form MSPs. Both NS formation and spin-up through accretion are greatly enhanced through dynamical interaction processes. We find that our models for average

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de Vita, Ruggero, Michele Trenti, and Morgan MacLeod. "Correlation between mass segregation and structural concentration in relaxed stellar clusters." Monthly Notices of the Royal Astronomical Society 485, no. 4 (2019): 5752–60. http://dx.doi.org/10.1093/mnras/stz815.

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Abstract The level of mass segregation in the core of globular clusters has been previously proposed as a potential indicator of the dynamical constituents of the system, such as presence of a significant population of stellar-mass black holes (BHs), or even a central intermediate-mass black hole (IMBH). However, its measurement is limited to clusters with high-quality Hubble Space Telescope data. Thanks to a set of state-of-the-art direct N-body simulations with up to 200k particles inclusive of stellar evolution, primordial binaries, and varying BH/neutron stars, we highlight for the first t

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Häberle, Maximilian, Mattia Libralato, Andrea Bellini, et al. "Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441." Monthly Notices of the Royal Astronomical Society 503, no. 1 (2021): 1490–506. http://dx.doi.org/10.1093/mnras/stab474.

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ABSTRACT We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centremost 15 arcsec of the cluster. We reach a PM precision of ∼30 µas yr−1 for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studie

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Gilliland, Ronald L., Peter D. Edmonds, Larry Petro, Abhijit Saha, and Michael Shara. "The Variable Star Population in the Center of 47 Tuc as denned by HST Observations." International Astronomical Union Colloquium 155 (1995): 335–36. http://dx.doi.org/10.1017/s0252921100037374.

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AbstractThe high stellar densities at the centre of some globular clusters provide prolific breeding grounds for exotic stars, e.g., the 11 msec pulsars in 47 Tuc and numerous blue stragglers. The same high density of stars as viewed on the sky makes ground-based photometry problematic for variable star detection. Even a very few tight binaries can be of fundamental importance for the dynamic evolution of the cluster core. We present results of a continuous 40-hour sequence of U-band CCD exposures acquired with WF/PC on HST. The high spatial resolution coupled with a stable PSF allows nearly P

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Cadelano, M., E. Dalessandro, J. J. Webb, et al. "Radial variation of the stellar mass functions in the globular clusters M15 and M30: clues of a non-standard IMF?" Monthly Notices of the Royal Astronomical Society 499, no. 2 (2020): 2390–400. http://dx.doi.org/10.1093/mnras/staa2759.

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ABSTRACT We exploit a combination of high-resolution Hubble Space Telescope and wide-field ESO-VLT observations to study the slope of the global mass function (αG) and its radial variation (α(r)) in the two dense, massive and post core-collapse globular clusters M15 and M30. The available data set samples the clusters’ main sequence down to ∼0.2 M⊙ and the photometric completeness allows the study of the mass function between 0.40 M⊙ and 0.75 M⊙ from the central regions out to their tidal radii. We find that both clusters show a very similar variation in α(r) as a function of clustercentric di

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McLaughlin, Dean E., Jay Anderson, Georges Meylan, et al. "Hubble Space Telescope Proper Motions and Stellar Dynamics in the Core of the Globular Cluster 47 Tucanae." Astrophysical Journal Supplement Series 166, no. 1 (2006): 249–97. http://dx.doi.org/10.1086/505692.

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Leung, Gigi Y. C., Ryan Leaman, Glenn van de Ven, and Giuseppina Battaglia. "A dwarf–dwarf merger and dark matter core as a solution to the globular cluster problems in the Fornax dSph." Monthly Notices of the Royal Astronomical Society 493, no. 1 (2019): 320–36. http://dx.doi.org/10.1093/mnras/stz3017.

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ABSTRACT The five globular clusters (GCs) of the Fornax dwarf spheroidal galaxy are puzzling for two reasons; the mass in GCs is high with respect to the galaxy’s old stellar mass and their survival and large distance (&gt;1 kpc) is at odds with naive expectations of dynamical friction. We present here a semi-analytic model, simultaneously addressing both problems in a comprehensive evolutionary framework for Fornax. Key to the model is inclusion of: (1) hydrodynamical constraints on the GC formation locations, (2) self-consistent velocity distribution functions in the dynamical friction c

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Wang, Yi-Han, Rosalba Perna, and Philip J. Armitage. "Partial tidal disruption events by stellar mass black holes: Gravitational instability of stream and impact from remnant core." Monthly Notices of the Royal Astronomical Society 503, no. 4 (2021): 6005–15. http://dx.doi.org/10.1093/mnras/stab802.

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ABSTRACT In dense star clusters, such as globular and open clusters, dynamical interactions between stars and black holes (BHs) can be extremely frequent, leading to various astrophysical transients. Close encounters between a star and a stellar mass BH make it possible for the star to be tidally disrupted by the BH. Due to the relative low mass of the BH and the small cross-section of the tidal disruption event (TDE) for cases with high penetration, disruptions caused by close encounters are usually partial disruptions. The existence of the remnant stellar core and its non-negligible mass com

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Pasquato, Mario, and Pierfrancesco Di Cintio. "Taking apart the dynamical clock." Astronomy & Astrophysics 640 (August 2020): A79. http://dx.doi.org/10.1051/0004-6361/201937279.

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Context. In globular clusters (GCs), blue straggler stars (BSS) are heavier than the average star, so dynamical friction strongly affects them. The radial distribution of BSS, normalized to a reference population, appears bimodal in a fraction of Galactic GCs, with a density peak in the core, a prominent zone of avoidance at intermediate radii, and again higher density in the outskirts. The zone of avoidance appears to be located at larger radii the more relaxed the host cluster, acting as a sort of dynamical clock. Aims. We use a new method to compute the evolution of the BSS radial distribut

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Pavlík, Václav, Tereza Jeřábková, Pavel Kroupa, and Holger Baumgardt. "The black hole retention fraction in star clusters." Astronomy & Astrophysics 617 (September 2018): A69. http://dx.doi.org/10.1051/0004-6361/201832919.

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Context. Recent research has been constraining the retention fraction of black holes (BHs) in globular clusters by comparing the degree of mass segregation with N-body simulations. They are consistent with an upper limit of the retention fraction being 50% or less. Aims. In this work, we focus on direct simulations of the dynamics of BHs in star clusters. We aim to constrain the effective distribution of natal kicks that BHs receive during supernova (SN) explosions and to estimate the BH retention fraction.Methods. We used the collisional N-body code nbody6 to measure the retention fraction of

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Anders, Peter, Uta Fritze –. v. Alvensleben, and Richard de Grijs. "Young Star Clusters: Progenitors of Globular Clusters!?" Highlights of Astronomy 13 (2005): 366–68. http://dx.doi.org/10.1017/s1539299600015987.

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AbstractStar cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. Young clusters are observed to form in a variety of such galaxies, a substantial number resembling the progenitors of globular clusters in mass and size, but with significantly enhanced metallicity. From studies of the metal-poor and metal-rich star cluster populations of galaxies, we can therefore learn about the violent star formation history of these galaxies, and eventually about galaxy formation and evolution. We present a new set of evolutionary synth

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Lee, Chris H., Edmund Hodges-Kluck, and Elena Gallo. "Ultraviolet and X-ray properties of Coma’s ultra-diffuse galaxies." Monthly Notices of the Royal Astronomical Society 497, no. 3 (2020): 2759–70. http://dx.doi.org/10.1093/mnras/staa1955.

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ABSTRACT Many ultra-diffuse galaxies (UDGs) have been discovered in the Coma cluster, and there is evidence that some, notably Dragonfly 44, have Milky Way-like dynamical masses despite dwarf-like stellar masses. We used X-ray, ultraviolet (UV), and optical data to investigate the star formation and nuclear activity in the Coma UDGs, and we obtained deep UV and X-ray data (Swift and XMM–Newton) for Dragonfly 44 to search for low-level star formation, hot circumgalactic gas, and the integrated emission from X-ray binaries. Among the Coma UDGs, we find UV luminosities consistent with quiescence

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Gandhi, P., A. Rao, P. A. Charles, et al. "A period-dependent spatial scatter of Galactic black hole transients." Monthly Notices of the Royal Astronomical Society: Letters 496, no. 1 (2020): L22—L27. http://dx.doi.org/10.1093/mnrasl/slaa081.

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ABSTRACT There remain significant uncertainties in the origin and evolution of black holes in binary systems, in particular regarding their birth sites and the influence of natal kicks. These are long-standing issues, but their debate has been reinvigorated in the era of gravitational wave detections and the improving precision of astrometric measurements. Using recent and archival characterization of Galactic black hole X-ray binaries (BHXBs), we report here an apparent anticorrelation between Porb (system orbital periods) and scatter in $z$ (elevation above the Galactic plane). The absence o

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Ramamani, Natarajan. "The Dynamics of Globular Cluster Systems." Symposium - International Astronomical Union 126 (1988): 641–42. http://dx.doi.org/10.1017/s0074180900043448.

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This paper describes a project whose aim is to study the dynamics of a globular cluster system using an N-body code modified to include the gravitational field of an isothermal galaxy model. The galaxy and the globular cluster system have the same radii, are spherically symmetric and non-rotating. The evolution is to be followed up to a Hubble time.

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Thomas, G. F., B. Famaey, R. Ibata, F. Renaud, N. F. Martin, and P. Kroupa. "Stellar streams as gravitational experiments." Astronomy & Astrophysics 609 (January 2018): A44. http://dx.doi.org/10.1051/0004-6361/201731609.

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Kinematically cold tidal streams of globular clusters (GC) are excellent tracers of the Galactic gravitational potential at moderate Galactocentric distances, and can also be used as probes of the law of gravity on Galactic scales. Here, we compare for the first time the generation of such streams in Newtonian and Milgromian gravity (MOND). We first computed analytical results to investigate the expected shape of the GC gravitational potential in both frameworks, and we then ran N-body simulations with the Phantom of Ramses code. We find that the GCs tend to become lopsided in MOND. This is a

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Cantiello, Michele, Aku Venhola, Aniello Grado, et al. "The Fornax Deep Survey with VST." Astronomy & Astrophysics 639 (July 2020): A136. http://dx.doi.org/10.1051/0004-6361/202038137.

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Context. A possible pathway for understanding the events and the mechanisms involved in galaxy formation and evolution is an in-depth investigation of the galactic and inter-galactic fossil sub-structures with long dynamical timescales: stars in the field and in stellar clusters. Aims. This paper continues the Fornax Deep Survey (FDS) series. Following previous studies dedicated to extended Fornax cluster members, we present the catalogs of compact stellar systems in the Fornax cluster, as well as extended background sources and point-like sources. Methods. We derived ugri photometry of ∼1.7 m

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Williams, Liliya L. R., Eric I. Barnes, and Jens Hjorth. "Collisionless dynamics in globular clusters." Monthly Notices of the Royal Astronomical Society 423, no. 4 (2012): 3589–600. http://dx.doi.org/10.1111/j.1365-2966.2012.21158.x.

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