Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

McKenzie, Madeleine; Bekki, Kenji

doi:10.1093/mnras/staa3376

Cited by 17 publications

(20 citation statements)

References 133 publications

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“…For example, it is not possible for the present study to investigate how the binary status of the simulated SCs can evolve over the next 2 Gyr (to the present time); will they merge to form a single SC, or not. We also cannot comment on how the simulated rotation can be less remarkable due to the two-body dynamical relaxation effects, and whether or not ISM can be accreted onto the new SCs to form new SCs, as discussed in recent papers (e.g., McKenzie & Bekki 2021a). We need to improve our modeling in star formation within GMCs, including more realistic feedback effects from massive stars with different masses (including supernovae).…”

Section: Future Work: From Sc Formation To Long-term Evolutionmentioning

confidence: 97%

“…We have already investigated a number of key physical processes related to SC formation such as GMC collisions during the LMC-SMC collision (e.g., Bekki et al 2004), gas accretion onto SCs (e.g., Bekki & Mackey 2009;Armstrong et al 2018), new star formation within massive globular clusters accreting gas from ISM (e.g., McKenzie & Bekki 2018;McKenzie & Bekki 2021a), and the roles of gas infall from the SMC to the LMC in SC formation (Bekki & Chiba 2007b;Tsuge et al 2019). We have not yet investigated the entire formation processes of SC formation from their natal GMCs.…”

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confidence: 99%

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Star cluster formation from giant molecular clouds in the Small Magellanic Cloud about 2 Gyr ago: their origin, structures, and kinematics

Williams,

Bekki,

McKenzie

2021

Preprint

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Recent observations have found that the age distribution of star clusters (SCs) in the Small Magellanic Cloud (SMC) shows a sharp peak around 2 Gyr ago. However, it is theoretically unclear what physical processes are responsible for such sudden formation of SCs in the SMC. Here we investigate whether massive SCs with initial masses more than 10 5 M can be formed during tidal interaction of the SMC with the Large Magellanic Cloud (LMC) about 2 Gyr ago, based on our new simulations, which include molecular hydrogen formation on dust grains and SC formation within giant molecular clouds (GMCs). We find that the formation of GMCs with masses more than 10 5 M can be dramatically enhanced due to the tidal force of the LMC-SMC interaction. We also find that gravitationally bound massive SCs can be formed within these GMCs, though their mean stellar densities (10 4 M pc −3 ) are systematically lower than those of the genuine globular clusters (GCs). All simulated SCs have diffuse extended stellar envelopes that were formed from multiple merging of sub clusters within their natal GMCs. Furthermore, we find that some of the simulated SCs can have considerable global internal rotation and substructures surrounding them. Based on these simulation results, we discuss the origin of the observed diverse properties of SCs in the SMC and the physical roles of galaxy interaction in the formation of massive SCs from GMCs.

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Section: Future Work: From Sc Formation To Long-term Evolutionmentioning

confidence: 97%

mentioning

confidence: 99%

Star cluster formation from giant molecular clouds in the Small Magellanic Cloud about 2 Gyr ago: their origin, structures, and kinematics

Williams,

Bekki,

McKenzie

2021

Preprint

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“…However, as it has been discussed in Section 1, the AGB ejecta alone are not able to reproduce the observed SG abundance patterns therefore they are generally assumed to be diluted with pristine gas. As in C19, we assume that the cluster is moving into a background distribution of gas representing the disk of a star-forming high-redshift galaxy (Kravtsov & Gnedin 2005;Bekki 2012;Kruĳssen 2015;McKenzie & Bekki 2021). The consequence of this motion is an asymmetric accretion of gas on the system from the side toward which the cluster is moving (Naiman et al 2011).…”

Section: Simulation Set-upmentioning

confidence: 99%

On the role of Type Ia supernovae in the second generation star formation in globular clusters

Lacchin,

Calura,

Vesperini

2021

Preprint

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By means of 3D hydrodynamic simulations, we study how Type Ia supernovae (SNe) explosions affect the star formation history and the chemical properties of second generation (SG) stars in globular clusters (GC). SG stars are assumed to form once first generation asymptotic giant branch (AGB) stars start releasing their ejecta; during this phase, external gas is accreted by the system and SNe Ia begin exploding, carving hot and tenuous bubbles. Given the large uncertainty on SNe Ia explosion times, we test two different values for the "delay time". We run two different models for the external gas density: in the low-density scenario with short delay time, the explosions start at the beginning of the SG star formation, halting it in its earliest phases. The external gas hardly penetrates the system, therefore most SG stars present extreme helium abundances (Y > 0.33). The low-density model with delayed SN explosions has a more extended SG star formation epoch and includes SG stars with modest helium enrichment. On the contrary, the high-density model is weakly affected by SN explosions, with a final SG mass similar to the one obtained without SNe Ia. Most of the stars form from a mix of AGB ejecta and pristine gas and have a modest helium enrichment. We show that gas from SNe Ia may produce an iron spread of ∼ 0.14 dex, consistent with the spread found in about 20% of Galactic GCs, suggesting that SNe Ia might have played a key role in the formation of this sub-sample of GCs.

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“…Another avenue are the much closer giant globular clusters 47 Tucanae (47 Tuc) and Omega Centauri Cen), also known as NGC 5139. These objects have distances of 4.4 and 5.5 kpc, respectively (Chen et al 2018; Del Principe et al 2006) and may be the nucleated remnants of ancient tidally-stripped dwarf galaxies (Peebles 1984; Norris et al 1996; Hilker & Richtler 2000; Bekki & Norris 2006; Lee et al 2009; McKenzie & Bekki 2021) and therefore in possible possession of a dark matter core. Various authors have suggested the role that dark matter may play in explaining their velocity dispersion profiles (e.g.…”

Section: Introductionmentioning

confidence: 99%

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

Bond

Bekki

Westmeier

2022

Publ. Astron. Soc. Aust.

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A plausible formation scenario for the Galactic globular clusters 47 Tucanae (47 Tuc) and Omega Centauri $(\omega$ Cen) is that they are tidally stripped remnants of dwarf galaxies, in which case they are likely to have retained a fraction of their dark matter cores. In this study, we have used the ultra-wide band receiver on the Parkes telescope (Murriyang) to place upper limits on the annihilation rate of exotic Light Dark Matter particles $(\chi)$ via the $\chi\chi\rightarrow e^+e^-$ channel using measurements of the recombination rate of positronium (Ps). This is an extension of a technique previously used to search for Ps in the Galactic Centre. However, by stacking of spectral data at multiple line frequencies, we have been able to improve sensitivity. Our measurements have resulted in $3-\sigma$ flux density (recombination rate) upper limits of 1.7 mJy $\left(1.4\times 10^{43}\, \mathrm{s}^{-1}\right)$ and 0.8 mJy $\left(1.1 \times 10^{43} \mathrm{s}^{-1}\right)$ for 47 Tuc and $\omega$ Cen, respectively. Within the Parkes beam at the cluster distances, which varies from 10–23 pc depending on the frequency of the recombination line, and for an assumed annihilation cross-section $\langle\sigma v\rangle = 3\times 10^{-29} \mathrm{cm}^3\, \mathrm{s}^{-1}$ , we calculate upper limits to the dark matter mass and rms dark matter density of ${\lesssim} 1.2-1.3\times 10^5 f_n^{-0.5}$ $\left(m_\chi/\mathrm{MeV\, c}^{-2}\right)$ $\mathrm{M}_{\odot}$ and ${\lesssim} 48-54 f_n^{-0.5}$ $\left(m_\chi/\mathrm{MeV\, c}^{-2}\right)$ $\mathrm{M}_{\odot} \mathrm{pc}^{-3}$ for the clusters, where $f_n=R_n/R_p$ is the ratio of Ps recombination transitions to annihilations, estimated to be ${\sim}0.01$ . The radio limits for $\omega$ Cen suggest that, for a fiducial dark/luminous mass ratio of ${\sim}0.05$ , any contribution from Light Dark Matter is small unless $\langle\sigma v\rangle < 7.9\times 10^{-28}\ \left(m_\chi/\mathrm{MeV\, c}^{-2}\right)^2 \mathrm{cm}^3 \mathrm{s}^{-1}$ . Owing to the compactness and proximity of the clusters, archival 511-keV measurements suggest even tighter limits than permitted by CMB anisotropies, $\langle\sigma v\rangle < 8.6\times 10^{-31}\ (m_\chi/\mathrm{MeV\, c}^{-2})^2 \mathrm{cm}^3 \mathrm{s}^{-1}$ . Due to the very low synchrotron radiation background, our recombination rate limits substantially improve on previous radio limits for the Milky Way.

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Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

Cited by 17 publications

References 133 publications

Star cluster formation from giant molecular clouds in the Small Magellanic Cloud about 2 Gyr ago: their origin, structures, and kinematics

Star cluster formation from giant molecular clouds in the Small Magellanic Cloud about 2 Gyr ago: their origin, structures, and kinematics

On the role of Type Ia supernovae in the second generation star formation in globular clusters

A search for annihilating dark matter in 47 Tucanae and Omega Centauri

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