scholarly journals Dynamics of black hole–neutron star binaries in young star clusters

2020 ◽  
Vol 497 (2) ◽  
pp. 1563-1570 ◽  
Author(s):  
Sara Rastello ◽  
Michela Mapelli ◽  
Ugo N Di Carlo ◽  
Nicola Giacobbo ◽  
Filippo Santoliquido ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Total Mass ◽  
Star Clusters ◽  
Cosmic Time ◽  
Young Star ◽  
Star Cluster ◽  
Population Synthesis ◽  
Compact Binaries ◽  
Young Star Clusters

ABSTRACT Young star clusters are likely the most common birthplace of massive stars across cosmic time and influence the formation of compact binaries in several ways. Here, we simulate the formation of black hole–neutron star binaries (BHNSs) in young star clusters, by means of the binary population synthesis code MOBSE interfaced with the N-body code NBODY6++GPU. BHNSs formed in young star clusters (dynamical BHNSs) are significantly more massive than BHNSs formed from isolated binaries (isolated BHNSs): ∼40 per cent of the dynamical BHNS mergers have a total mass of >15 M⊙, while only ∼0.01 per cent of the isolated BHNS mergers have mass in excess of this value. Hence, our models strongly support a dynamical formation scenario for GW190814, given its total mass of ∼26 M⊙, if this event is a BHNS merger. All our dynamical BHNSs are ejected from their parent star cluster before they reach coalescence. Thus, a significant fraction of BHNS mergers occurring in the field might have originated in a young star cluster. The mass spectrum of BHNS mergers from gravitational-wave detections will provide a clue to differentiate between dynamical and isolated formation of BHNSs.

Black Hole dynamics in Young Star Clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 490-493
Author(s):  
Sara Rastello ◽  
Ugo N. di Carlo ◽  
Michela Mapelli ◽  
Nicola Giacobbo ◽  
Alessandro Ballone
Keyword(s):  
Black Hole ◽  
Binary Star ◽  
Star Clusters ◽  
Young Star ◽  
Population Synthesis ◽  
Massive Black Hole ◽  
Binary Black Holes ◽  
Black Hole Binaries ◽  
Low Mass ◽  
Young Star Clusters

AbstractYoung star clusters are a promising environment for forming binary black holes. Such binaries may form dynamically or via binary star evolution or through the interplay of these two channels. To study these formation pathways, we have performed high precision direct N-body simulations of low-mass (M < 1000 M⊙) young star clusters. The simulations were carried out with the code Nbody6++GPU coupled with the population synthesis code MOBSE. Our results highlight the importance of dynamics to form massive black hole binaries even in low-mass young star clusters.

scholarly journals The R136 star cluster dissected withHubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of He ii λ1640 in young star clusters

2016 ◽  
Vol 458 (1) ◽  
pp. 624-659 ◽  
Author(s):  
Paul A. Crowther ◽  
S. M. Caballero-Nieves ◽  
K. A. Bostroem ◽  
J. Maíz Apellániz ◽  
F. R. N. Schneider ◽  
...  
Keyword(s):  
Star Clusters ◽  
Young Star ◽  
Star Cluster ◽  
Space Telescope ◽  
Far Ultraviolet ◽  
Young Star Clusters

scholarly journals Hierarchical black hole triples in young star clusters: impact of Kozai–Lidov resonance on mergers

2016 ◽  
Vol 463 (3) ◽  
pp. 2443-2452 ◽  
Author(s):  
Thomas O. Kimpson ◽  
Mario Spera ◽  
Michela Mapelli ◽  
Brunetto M. Ziosi
Keyword(s):  
Black Hole ◽  
Star Clusters ◽  
Young Star ◽  
Young Star Clusters

scholarly journals New insights on binary black hole formation channels after GWTC-2: young star clusters versus isolated binaries

2021 ◽  
Author(s):  
Yann Bouffanais ◽  
Michela Mapelli ◽  
Filippo Santoliquido ◽  
Nicola Giacobbo ◽  
Ugo N Di Carlo ◽  
...  
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Star Clusters ◽  
Credible Interval ◽  
Young Star ◽  
Compact Objects ◽  
Bayesian Hierarchical ◽  
Binary Black Hole ◽  
Higher Spin ◽  
Young Star Clusters

Abstract With the recent release of the second gravitational-wave transient catalogue (GWTC-2), which introduced dozens of new detections, we are at a turning point of gravitational wave astronomy, as we are now able to directly infer constraints on the astrophysical population of compact objects. Here, we tackle the burning issue of understanding the origin of binary black hole (BBH) mergers. To this effect, we make use of state-of-the-art population synthesis and N-body simulations, to represent two distinct formation channels: BBHs formed in the field (isolated channel) and in young star clusters (dynamical channel). We then use a Bayesian hierarchical approach to infer the distribution of the mixing fraction f, with f = 0 (f = 1) in the pure dynamical (isolated) channel. We explore the effects of additional hyper-parameters of the model, such as the spread in metallicity σZ and the parameter σsp, describing the distribution of spin magnitudes. We find that the dynamical model is slightly favoured with a median value of f = 0.26, when σsp = 0.1 and σZ = 0.4. Models with higher spin magnitudes tend to strongly favour dynamically formed BBHs (f ≤ 0.1 if σsp = 0.3). Furthermore, we show that hyper-parameters controlling the rates of the model, such as σZ, have a large impact on the inference of the mixing fraction, which rises from 0.18 to 0.43 when we increase σZ from 0.2 to 0.6, for a fixed value of σsp = 0.1. Finally, our current set of observations is better described by a combination of both formation channels, as a pure dynamical scenario is excluded at the $99{{\ \rm per\ cent}}$ credible interval, except when the spin magnitude is high.

scholarly journals The Cosmic Merger Rate Density Evolution of Compact Binaries Formed in Young Star Clusters and in Isolated Binaries

2020 ◽  
Vol 898 (2) ◽  
pp. 152 ◽  
Author(s):  
Filippo Santoliquido ◽  
Michela Mapelli ◽  
Yann Bouffanais ◽  
Nicola Giacobbo ◽  
Ugo N. Di Carlo ◽  
...  
Keyword(s):  
Star Clusters ◽  
Young Star ◽  
Density Evolution ◽  
Compact Binaries ◽  
Merger Rate ◽  
Young Star Clusters

scholarly journals Ages and Masses of Star Clusters in M33: a Multiwavelength Study

2021 ◽  
Vol 163 (1) ◽  
pp. 16
Author(s):  
Caitlin Moeller ◽  
Daniela Calzetti
Keyword(s):  
Spectral Energy Distribution ◽  
Star Clusters ◽  
Young Star ◽  
Star Cluster ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Nearby Galaxy ◽  
Population Synthesis ◽  
Cluster Evolution ◽  
The Masses

Abstract We combine archival images for the nearby galaxy M33 (Triangulum Galaxy) from the ultraviolet (UV) to the infrared to derive ages, masses, and extinctions for the young star cluster population, and compare our physical parameters with published ones. Our goal is to test the robustness of clusters ages and masses, and possibly improve on existing ones both by expanding the wavelength range of the spectral-energy distribution (SED) fits and by using more recent population synthesis models. The rationale for this experiment is to verify the sensitivity of the clusters physical parameters to observational setups and model choices that span those commonly found in the literature. We derive the physical parameters of 137 clusters, using SEDs measured in eight UV-to-I bands, including Hα, from GALEX and ground-based images. We also add the 24 μm image from the Spitzer Space Telescope to help break some age degeneracies. We find that our derived cluster ages show significant differences with earlier determinations, while the masses remain relatively insensitive to the fitting approach adopted. We also highlight an already known difficulty in recovering old, low-extinction clusters, as SED-fitting codes tend to prefer younger, higher extinction solutions when the extinction is a free parameter. We publish updated ages, masses, and extinctions, with uncertainties for all sample star clusters, together with their photometry. Given the proximity of M33, this represents an important population to secure for the study of star formation and cluster evolution in spirals.

scholarly journals Young Star Clusters: Progenitors of Globular Clusters!?

2005 ◽  
Vol 13 ◽  
pp. 366-368
Author(s):  
Peter Anders ◽  
Uta Fritze – v. Alvensleben ◽  
Richard de Grijs
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Star Clusters ◽  
Young Star ◽  
Star Cluster ◽  
Star Formation History ◽  
Starburst Galaxy ◽  
Major Mode ◽  
Young Clusters ◽  
Young Star Clusters

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 synthesis models of our GALEV code, with special emphasis on the gaseous emission of presently forming star clusters, and a new tool to compare extensive model grids with multi-color broad-band observations to determine individual cluster masses, metallicities, ages and extinction values independently. First results for young star clusters in the dwarf starburst galaxy NGC 1569 are presented. The mass distributions determined for the young clusters give valuable input to dynamical star cluster system evolution models, regarding survival and destruction of clusters. We plan to investigate an age sequence of galaxy mergers to see dynamical destruction effects in process.

scholarly journals GW190521 formation via three-body encounters in young massive star clusters

2021 ◽  
Author(s):  
Marco Dall’Amico ◽  
Michela Mapelli ◽  
Ugo N Di Carlo ◽  
Yann Bouffanais ◽  
Sara Rastello ◽  
...  
Keyword(s):  
Black Hole ◽  
First Generation ◽  
Massive Star ◽  
Second Generation ◽  
Star Clusters ◽  
Young Star ◽  
Mass Gap ◽  
Stellar Collisions ◽  
Three Body ◽  
Young Star Clusters

Abstract GW190521 is the most massive binary black hole (BBH) merger observed to date, and its primary component lies in the pair-instability (PI) mass gap. Here, we investigate the formation of GW190521-like systems via three-body encounters in young massive star clusters. We performed 2× 105 simulations of binary-single interactions between a BBH and a massive ≥60 M⊙ black hole (BH), including post-Newtonian terms up to the 2.5 order and a prescription for relativistic kicks. In our initial conditions, we take into account the possibility of forming BHs in the PI mass gap via stellar collisions. If we assume that first-generation BHs have low spins, $\sim {0.17}{{\ \rm per\ cent}}$ of all the simulated BBH mergers have component masses, effective and precessing spin, and remnant mass and spin inside the $90{{\ \rm per\ cent}}$ credible intervals of GW190521. Seven of these systems are first-generation exchanged binaries, while five are second-generation BBHs. We estimate a merger rate density $\mathcal {R}_{\rm GW190521}\sim {0.03}\,$Gpc−3 yr−1 for GW190521-like binaries formed via binary-single interactions in young star clusters. This rate is extremely sensitive to the spin distribution of first-generation BBHs. Stellar collisions, second-generation mergers and dynamical exchanges are the key ingredients to produce GW190521-like systems in young star clusters.

scholarly journals Gamma-rays from massive stars in Cygnus and Orion

2003 ◽  
Vol 212 ◽  
pp. 706-709 ◽  
Author(s):  
Roland Diehl ◽  
Karsten Kretschmer ◽  
Stefan Plüschke ◽  
Miguel Cerviño ◽  
Dieter H. Hartmann
Keyword(s):  
Gamma Rays ◽  
Massive Stars ◽  
Line Emission ◽  
Star Clusters ◽  
Young Star ◽  
Synthesis Methods ◽  
Population Synthesis ◽  
Supernova Explosions ◽  
Γ Ray ◽  
Young Star Clusters

Radioactive 26Al, ejected by massive stars through winds and supernova explosions, leads to γ-ray line emission that can serve as a probe of the interstellar environment in and near young star clusters. The ~ 1 Myr decay time of 26Al is long enough to allow transport over significant distances, which can cause substantial angular offsets between γ-ray emission and cluster stars. Details of such offsets are determined by the morphology of the ISM. We discuss observations in Cygnus and Orion, and models based on population synthesis methods.

scholarly journals Star clusters as building blocks for dSph galaxy formation

2009 ◽  
Vol 5 (S266) ◽  
pp. 353-356
Author(s):  
P. Assmann ◽  
M. Fellhauer ◽  
M. I. Wilkinson
Keyword(s):  
Dark Matter ◽  
Numerical Experiment ◽  
Galaxy Formation ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Building Blocks ◽  
Young Star ◽  
Star Cluster ◽  
Cluster Complexes ◽  
Young Star Clusters

AbstractWe study numerically the formation of dSph galaxies. Intense starbursts, e.g., in gas-rich environments, typically produce a few to a few hundred young star clusters within a region of just a few hundred pc. The dynamical evolution of these star clusters may explain the formation of the luminous component of dwarf spheroidal (dSph) galaxies. Here, we perform a numerical experiment to show that the evolution of star cluster complexes in dark-matter haloes can explain the formation of the luminous components of dSph galaxies.

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