scholarly journals Breaching the Limit: Formation of GW190521-like and IMBH Mergers in Young Massive Clusters

2021 ◽  
Vol 920 (2) ◽  
pp. 128
Author(s):  
Manuel Arca-Sedda ◽  
Francesco Paolo Rizzuto ◽  
Thorsten Naab ◽  
Jeremiah Ostriker ◽  
Mirek Giersz ◽  
...  
Keyword(s):  
Massive Clusters

scholarly journals Are we observing an NSC in course of formation in the NGC 4654 galaxy?

2021 ◽  
Vol 503 (1) ◽  
pp. 594-602
Author(s):  
R Schiavi ◽  
R Capuzzo-Dolcetta ◽  
I Y Georgiev ◽  
M Arca-Sedda ◽  
A Mastrobuono-Battisti
Keyword(s):  
Central Zone ◽  
Effective Radius ◽  
Host Galaxy ◽  
Galactic Centre ◽  
Future Evolution ◽  
Orbital Parameters ◽  
Relative Orbit ◽  
The Future ◽  
The Galaxy ◽  
Massive Clusters

ABSTRACT We use direct N-body simulations to explore some possible scenarios for the future evolution of two massive clusters observed towards the centre of NGC 4654, a spiral galaxy with mass similar to that of the Milky Way. Using archival HST data, we obtain the photometric masses of the two clusters, M = 3 × 105 M⊙ and M = 1.7 × 106 M⊙, their half-light radii, Reff ∼ 4 pc and Reff ∼ 6 pc, and their projected distances from the photometric centre of the galaxy (both <22 pc). The knowledge of the structure and separation of these two clusters (∼24 pc) provides a unique view for studying the dynamics of a galactic central zone hosting massive clusters. Varying some of the unknown cluster orbital parameters, we carry out several N-body simulations showing that the future evolution of these clusters will inevitably result in their merger. We find that, mainly depending on the shape of their relative orbit, they will merge into the galactic centre in less than 82 Myr. In addition to the tidal interaction, a proper consideration of the dynamical friction braking would shorten the merging times up to few Myr. We also investigate the possibility to form a massive nuclear star cluster (NSC) in the centre of the galaxy by this process. Our analysis suggests that for low-eccentricity orbits, and relatively long merger times, the final merged cluster is spherical in shape, with an effective radius of few parsecs and a mass within the effective radius of the order of $10^5\, \mathrm{M_{\odot }}$. Because the central density of such a cluster is higher than that of the host galaxy, it is likely that this merger remnant could be the likely embryo of a future NSC.

scholarly journals The accreted nuclear clusters of the Milky Way

2020 ◽  
Vol 500 (2) ◽  
pp. 2514-2524
Author(s):  
Joel Pfeffer ◽  
Carmela Lardo ◽  
Nate Bastian ◽  
Sara Saracino ◽  
Sebastian Kamann
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
Host Galaxy ◽  
The Galaxy ◽  
Nuclear Clusters ◽  
The Common ◽  
Massive Clusters ◽  
Peculiar Case

ABSTRACT A number of the massive clusters in the halo, bulge, and disc of the Galaxy are not genuine globular clusters (GCs) but instead are different beasts altogether. They are the remnant nuclear star clusters (NSCs) of ancient galaxies since accreted by the Milky Way. While some clusters are readily identifiable as NSCs and can be readily traced back to their host galaxy (e.g. M54 and the Sagittarius Dwarf galaxy), others have proven more elusive. Here, we combine a number of independent constraints, focusing on their internal abundances and overall kinematics, to find NSCs accreted by the Galaxy and trace them to their accretion event. We find that the true NSCs accreted by the Galaxy are: M54 from the Sagittarius Dwarf, ω Centari from Gaia-Enceladus/Sausage, NGC 6273 from Kraken, and (potentially) NGC 6934 from the Helmi Streams. These NSCs are prime candidates for searches of intermediate-mass black holes (BHs) within star clusters, given the common occurrence of galaxies hosting both NSCs and central massive BHs. No NSC appears to be associated with Sequoia or other minor accretion events. Other claimed NSCs are shown not to be such. We also discuss the peculiar case of Terzan 5, which may represent a unique case of a cluster–cluster merger.

scholarly journals The Formation of Massive Stars

2010 ◽  
Vol 6 (S270) ◽  
pp. 57-64
Author(s):  
Ian A. Bonnell ◽  
Rowan J Smith
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Massive Star ◽  
Massive Stars ◽  
Cluster Formation ◽  
High Mass ◽  
Prestellar Cores ◽  
Stellar Mergers ◽  
Massive Clusters ◽  
Viable Mechanism

AbstractThere has been considerable progress in our understanding of how massive stars form but still much confusion as to why they form. Recent work from several sources has shown that the formation of massive stars through disc accretion, possibly aided by gravitational and Rayleigh-Taylor instabilities is a viable mechanism. Stellar mergers, on the other hand, are unlikely to occur in any but the most massive clusters and hence should not be a primary avenue for massive star formation. In contrast to this success, we are still uncertain as to how the mass that forms a massive star is accumulated. there are two possible mechanisms including the collapse of massive prestellar cores and competitive accretion in clusters. At present, there are theoretical and observational question marks as to the existence of high-mass prestellar cores. theoretically, such objects should fragment before they can attain a relaxed, centrally condensed and high-mass state necessary to form massive stars. Numerical simulations including cluster formation, feedback and magnetic fields have not found such objects but instead point to the continued accretion in a cluster potential as the primary mechanism to form high-mass stars. Feedback and magnetic fields act to slow the star formation process and will reduce the efficiencies from a purely dynamical collapse but otherwise appear to not significantly alter the process.

scholarly journals Do you know the extinction in your young massive cluster?

2015 ◽  
Vol 12 (S316) ◽  
pp. 137-138
Author(s):  
Guido De Marchi ◽  
Nino Panagia ◽  
Elena Sabbi
Keyword(s):  
Interstellar Medium ◽  
Local Extinction ◽  
Type Ii ◽  
Effective Temperatures ◽  
Young Clusters ◽  
Massive Clusters ◽  
Massive Cluster

Up to ages of ~ 100 Myr, massive clusters are still swamped in large amounts of gas and dust, with considerable and uneven levels of extinction. At the same time, large grains (ices?) produced by type II supernovae profoundly alter the interstellar medium (ISM), thus resulting in extinction properties very different from those of the diffuse ISM. To obtain physically meaningful parameters of stars, from basic luminosities and effective temperatures to masses and ages, we must understand and measure the local extinction law. This problem affects all the massive young clusters discussed in his volume.

scholarly journals MASER OBSERVATIONS OF WESTERLUND 1 AND COMPREHENSIVE CONSIDERATIONS ON MASER PROPERTIES OF RED SUPERGIANTS ASSOCIATED WITH MASSIVE CLUSTERS

2012 ◽  
Vol 760 (1) ◽  
pp. 65 ◽  
Author(s):  
Thomas K. T. Fok ◽  
Jun-ichi Nakashima ◽  
Bosco H. K. Yung ◽  
Chih-Hao Hsia ◽  
Shuji Deguchi
Keyword(s):  
Red Supergiants ◽  
Massive Clusters

scholarly journals Bimodal regime in young massive clusters leading to subsequent stellar generations

2015 ◽  
Vol 12 (S316) ◽  
pp. 294-301
Author(s):  
Richard Wünsch ◽  
Jan Palouš ◽  
Guillermo Tenorio-Tagle ◽  
Casiana Muñoz-Tuñón ◽  
Soňa Ehlerová
Keyword(s):  
Stellar Evolution ◽  
Column Density ◽  
First Generation ◽  
Massive Stars ◽  
Ionising Radiation ◽  
Cluster Center ◽  
Stellar Winds ◽  
Hot Gas ◽  
Massive Clusters ◽  
By Products

AbstractMassive stars in young massive clusters insert tremendous amounts of mass and energy into their surroundings in the form of stellar winds and supernova ejecta. Mutual shock-shock collisions lead to formation of hot gas, filling the volume of the cluster. The pressure of this gas then drives a powerful cluster wind. However, it has been shown that if the cluster is massive and dense enough, it can evolve in the so–called bimodal regime, in which the hot gas inside the cluster becomes thermally unstable and forms dense clumps which are trapped inside the cluster by its gravity. We will review works on the bimodal regime and discuss the implications for the formation of subsequent stellar generations. The mass accumulates inside the cluster and as soon as a high enough column density is reached, the interior of the clumps becomes self-shielded against the ionising radiation of stars and the clumps collapse and form new stars. The second stellar generation will be enriched by products of stellar evolution from the first generation, and will be concentrated near the cluster center.

scholarly journals The implications of bent jets in galaxy groups

2014 ◽  
Vol 10 (S313) ◽  
pp. 303-304
Author(s):  
Danielle M. Nielsen ◽  
Eric M. Wilcots
Keyword(s):  
High Velocity ◽  
Velocity Dispersion ◽  
Radio Continuum ◽  
Dense Medium ◽  
Lower Mass ◽  
Galaxy Groups ◽  
Turbulent Environments ◽  
Narrow Angle ◽  
Ram Pressure ◽  
Massive Clusters

AbstractBent-double sources, sometimes referred to as wide- or narrow-angle tails, are most likely the result of ram pressure from either the motion of the source through a dense medium or the "cluster weather." These unusual sources have long been associated with high density, high velocity dispersion, and turbulent environments of massive clusters, however a surprising number have been found in lower mass systems. We focus our attention on a sample of such sources in galaxy groups where the velocity dispersion is significantly lower. We have acquired multi-frequency radio continuum observations using the GMRT of our bent-double sample and new optical spectroscopy to measure the velocity dispersion of groups hosting these bent-double sources. Our goal is to derive an estimate of the density of the intergalactic medium in these groups. Here, we present GMRT data for one source in our sample.

Sign in / Sign up

Export Citation Format

Share Document