scholarly journals Modeling Formation of Globular Clusters: Beacons of Galactic Star Formation

2010 ◽  
Vol 6 (S270) ◽  
pp. 381-384
Author(s):  
Oleg Y. Gnedin
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Star Clusters ◽  
Mass Function ◽  
Giant Molecular Clouds ◽  
Early Galaxies ◽  
The Masses

AbstractModern hydrodynamic simulations of galaxy formation are able to predict accurately the rates and locations of the assembly of giant molecular clouds in early galaxies. These clouds could host star clusters with the masses and sizes of real globular clusters. I describe current state-of-the-art simulations aimed at understanding the origin of the cluster mass function and metallicity distribution. Metallicity bimodality of globular cluster systems appears to be a natural outcome of hierarchical formation and gradually declining fraction of cold gas in galaxies. Globular cluster formation was most prominent at redshifts z > 3, when massive star clusters may have contributed as much as 20% of all galactic star formation.

scholarly journals The Formation and Evolution of Star Clusters and Galaxies

2005 ◽  
Vol 13 ◽  
pp. 347-349
Author(s):  
Stephen E. Zepf
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Near Infrared ◽  
Cluster Formation ◽  
Star Clusters ◽  
Elliptical Galaxies ◽  
Cluster Systems ◽  
Important Observation ◽  
Formation And Evolution

AbstractThis paper addresses the questions of what we have learned about how and when dense star clusters form, and what studies of star clusters have revealed about galaxy formation and evolution. One important observation is that globular clusters are observed to form in galaxy mergers and starbursts in the local universe, which both provides constraints on models of globular cluster formation, and suggests that similar physical conditions existed when most early-type galaxies and their globular clusters formed in the past. A second important observation is that globular cluster systems typically have bimodal color distributions. This was predicted by merger models, and indicates an episodic formation history for elliptical galaxies. A third and very recent result is the discovery of large populations of intermediate age globular clusters in several elliptical galaxies through the use of optical to near-infrared colors. These provide an important link between young cluster systems observed in starbursts and mergers and old cluster systems. This continuum of ages of the metal-rich globular cluster systems also indicates that there is no special age or epoch for the formation of the metal-rich globular clusters, which comprise about half of the cluster population. The paper concludes with a brief discussion of recent results on the globular cluster – low-mass X-ray binary connection.

scholarly journals The Formation of Globular Cluster Systems: how, when, and where?

1996 ◽  
Vol 171 ◽  
pp. 87-95
Author(s):  
William E. Harris
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Star Clusters ◽  
Cluster Systems ◽  
The Right

Globular clusters, as fossil remnants of the protogalactic era, provide unique traces of the earliest events of galaxy formation. However, new observations – especially from HST – are showing that massive, globular-like star clusters belong not only to the pregalactic era but can form right up to the present day under the right circumstances. Appropriate interpretation may now let us learnsimultaneouslyabout the process of cluster formation as well as the nature of the gaseous fragments from which the galaxies were assembled.

scholarly journals Dynamical Evolution of Globular Clusters in Hierarchical Cosmology

2007 ◽  
Vol 3 (S246) ◽  
pp. 403-407
Author(s):  
Oleg Y. Gnedin ◽  
José L. Prieto
Keyword(s):  
Galaxy Formation ◽  
Power Law ◽  
Molecular Clouds ◽  
Globular Clusters ◽  
High Redshift ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Giant Molecular Clouds ◽  
Log Normal ◽  
The Masses

AbstractWe probe the evolution of globular clusters that could form in giant molecular clouds within high-redshift galaxies. Numerical simulations demonstrate that the large and dense enough gas clouds assemble naturally in current hierarchical models of galaxy formation. These clouds are enriched with heavy elements from earlier stars and could produce star clusters in a similar way to nearby molecular clouds. The masses and sizes of the model clusters are in excellent agreement with the observations of young massive clusters. Do these model clusters evolve into globular clusters that we see in our and external galaxies? In order to study their dynamical evolution, we calculate the orbits of model clusters using the outputs of the cosmological simulation of a Milky Way-sized galaxy. We find that at present the orbits are isotropic in the inner 50 kpc of the Galaxy and preferentially radial at larger distances. All clusters located outside 10 kpc from the center formed in the now-disrupted satellite galaxies. The spatial distribution of model clusters is spheroidal, with a power-law density profile consistent with observations. The combination of two-body scattering, tidal shocks, and stellar evolution results in the evolution of the cluster mass function from an initial power law to the observed log-normal distribution.

scholarly journals Star and Globular Cluster Formation in Mergers

1996 ◽  
Vol 171 ◽  
pp. 376-376
Author(s):  
Uta Fritze - v. Alvensleben
Keyword(s):  
Star Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Star Clusters ◽  
Young Star ◽  
Evolutionary Synthesis ◽  
Secondary Population ◽  
Ngc 1275 ◽  
Young Star Clusters

The high burst strengths and star formation efficiencies found with spectrophotmetric and chemical evolutionary synthesis for mergers of gas-rich spirals led us to expect the formation of a secondary population of globular clusters (GC) with enhanced metallicity (F. – v. A. & Gerhard 1994, A&A 285, 751 u.775). HST imaging of NGC 7252, NGC 4038/39 and NGC 1275 revealed rich populations of bright young star clusters (YSC).

scholarly journals Effects of initial density profiles on massive star cluster formation in giant molecular clouds

2021 ◽  
Author(s):  
Yingtian Chen ◽  
Hui Li ◽  
Mark Vogelsberger
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Molecular Clouds ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Initial Density ◽  
Giant Molecular Clouds ◽  
Density Profiles ◽  
Stellar Feedback ◽  
Gas Accretion

Abstract We perform a suite of hydrodynamic simulations to investigate how initial density profiles of giant molecular clouds (GMCs) affect their subsequent evolution. We find that the star formation duration and integrated star formation efficiency of the whole clouds are not sensitive to the choice of different profiles but are mainly controlled by the interplay between gravitational collapse and stellar feedback. Despite this similarity, GMCs with different profiles show dramatically different modes of star formation. For shallower profiles, GMCs first fragment into many self-gravitation cores and form sub-clusters that distributed throughout the entire clouds. These sub-clusters are later assembled ‘hierarchically’ to central clusters. In contrast, for steeper profiles, a massive cluster is quickly formed at the center of the cloud and then gradually grows its mass via gas accretion. Consequently, central clusters that emerged from clouds with shallower profiles are less massive and show less rotation than those with the steeper profiles. This is because 1) a significant fraction of mass and angular momentum in shallower profiles is stored in the orbital motion of the sub-clusters that are not able to merge into the central clusters 2) frequent hierarchical mergers in the shallower profiles lead to further losses of mass and angular momentum via violent relaxation and tidal disruption. Encouragingly, the degree of cluster rotations in steeper profiles is consistent with recent observations of young and intermediate-age clusters. We speculate that rotating globular clusters are likely formed via an ‘accretion’ mode from centrally-concentrated clouds in the early Universe.

scholarly journals Star-cluster formation and evolution

2006 ◽  
Vol 2 (S237) ◽  
pp. 230-237 ◽  
Author(s):  
Pavel Kroupa
Keyword(s):  
Galaxy Formation ◽  
Cluster Formation ◽  
Star Clusters ◽  
Mass Function ◽  
Cluster Mass ◽  
Cluster Evolution ◽  
Stellar Component ◽  
Galaxy Formation And Evolution ◽  
Dynamical Time ◽  
Formation And Evolution

AbstractStar clusters are observed to form in a highly compact state and with low star-formation efficiencies, and only 10 per cent of all clusters appear to survive to middle- and old-dynamical age. If the residual gas is expelled on a dynamical time the clusters disrupt. Massive clusters may then feed a hot kinematical stellar component into their host-galaxy's field population thereby thickening galactic disks, a process that theories of galaxy formation and evolution need to accommodate. If the gas-evacuation time-scale depends on cluster mass, then a power-law embedded-cluster mass function may transform within a few dozen Myr to a mass function with a turnover near 105M, thereby possibly explaining this universal empirical feature. Discordant empirical evidence on the mass function of star clusters leads to the insight that the physical processes shaping early cluster evolution remain an issue of cutting-edge research.

scholarly journals The nature and nurture of star clusters

2009 ◽  
Vol 5 (S266) ◽  
pp. 3-13 ◽  
Author(s):  
Bruce G. Elmegreen
Keyword(s):  
Globular Clusters ◽  
Dwarf Galaxy ◽  
Cluster Formation ◽  
Star Clusters ◽  
Mass Function ◽  
Radial Gradient ◽  
Cluster Mass ◽  
Low Mass ◽  
Nature And Nurture ◽  
Gas Loss

AbstractStar clusters have hierarchical patterns in space and time, suggesting formation processes in the densest regions of a turbulent interstellar medium. Clusters also have hierarchical substructure when they are young, which makes them all look like the inner mixed parts of a pervasive stellar hierarchy. Young field stars share this distribution, presumably because some of them came from dissolved clusters and others formed in a dispersed fashion in the same gas. The fraction of star formation that ends up in clusters is apparently not constant, but may increase with interstellar pressure. Hierarchical structure explains why stars form in clusters and why many of these clusters are self-bound. It also explains the cluster mass function. Halo globular clusters share many properties of disk clusters, including what appears to be an upper cluster cutoff mass. However, halo globulars are self-enriched and often connected with dwarf galaxy streams. The mass function of halo globulars could have initially been like the power-law mass function of disk clusters, but the halo globulars have lost their low-mass members. The reasons for this loss are not understood. It could have happened slowly over time as a result of cluster evaporation, or it could have happened early after cluster formation as a result of gas loss. The latter model explains best the observation that the globular cluster mass function has no radial gradient in galaxies.

scholarly journals Witnessing globular cluster formation at z ∼ 3–10 with JWST and ELT

2019 ◽  
Vol 15 (S352) ◽  
pp. 33-37
Author(s):  
Alvio Renzini
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Early Stages

AbstractThe opportunities offered by JWST and the ELT for the detection and study of forming/just formed globular clusters at high redshifts are illustrated, also alluding at the unique insight we may get on the very early stages of galaxy formation.

scholarly journals On the origin of globular cluster bimodality

2009 ◽  
Vol 5 (S266) ◽  
pp. 250-257
Author(s):  
Oleg Y. Gnedin
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Bimodal Distribution ◽  
Mass Function ◽  
Common Mechanism ◽  
Host Galaxies ◽  
Best Fitting ◽  
Galaxy Assembly ◽  
Fitting Model

AbstractGlobular cluster systems in most large galaxies display bimodal color and metallicity distributions, which are frequently interpreted as indicating two distinct modes of cluster formation. The metal-rich (red) and metal-poor (blue) clusters have systematically different locations and kinematics in their host galaxies. However, the red and blue clusters have similar internal properties, such as their masses, sizes, and ages. It is therefore interesting to explore whether both metal-rich and metal-poor clusters could form by a common mechanism and still be consistent with the bimodal distribution. We show that if all globular clusters form only during mergers of massive, gas-rich protogalactic disks, their metallicity distribution could be statistically consistent with that of the Galactic globulars. We take the galaxy assembly history from cosmological dark-matter simulations and couple it with the observed scaling relations for the amount of cold gas available for star formation. In the best-fitting model, early mergers of smaller hosts create exclusively blue clusters, while subsequent mergers of progenitor galaxies with a range of masses create both red and blue clusters. Thus, bimodality arises naturally as the result of a small number of late, massive merger events. We calculate cluster mass loss, including the effects of two-body scattering and stellar evolution, and find that more blue than red clusters are disrupted by the present time because of their lower initial masses and older ages. The present-day mass function in the best-fitting model is consistent with the Galactic distribution. However, the spatial distribution of model clusters is much more extended than observed and is independent of the parameters of our model.

scholarly journals Star Clusters Near and Far

2020 ◽  
Vol 216 (4) ◽  
Author(s):  
Angela Adamo ◽  
Peter Zeidler ◽  
J. M. Diederik Kruijssen ◽  
Mélanie Chevance ◽  
Mark Gieles ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Globular Clusters ◽  
High Redshift ◽  
Cluster Formation ◽  
Star Clusters ◽  
Local Universe ◽  
Stellar Feedback ◽  
Formation And Evolution ◽  
Numerical And Analytical Methods ◽  
Fundamental Units

Abstract Star clusters are fundamental units of stellar feedback and unique tracers of their host galactic properties. In this review, we will first focus on their constituents, i.e. detailed insight into their stellar populations and their surrounding ionised, warm, neutral, and molecular gas. We, then, move beyond the Local Group to review star cluster populations at various evolutionary stages, and in diverse galactic environmental conditions accessible in the local Universe. At high redshift, where conditions for cluster formation and evolution are more extreme, we are only able to observe the integrated light of a handful of objects that we believe will become globular clusters. We therefore discuss how numerical and analytical methods, informed by the observed properties of cluster populations in the local Universe, are used to develop sophisticated simulations potentially capable of disentangling the genetic map of galaxy formation and assembly that is carried by globular cluster populations.

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