Ionizing feedback effects on star formation in globular clusters with multiple stellar populations

Yaghoobi, Asiyeh; Rosdahl, Joakim; Calura, F.; Khalaj, Pouria; Haghi, Hosein

doi:10.1093/mnras/stac2941

Cited by 4 publications

(1 citation statement)

References 76 publications

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“…following the Supernovae type II (SN II) epoch, during which the massive AGB winds accumulate in a central cooling flow and form the second generation stars, as envisioned by the AGB model (D'Ercole et al 2008(D'Ercole et al , 2016 and now supported by 3D hydrodynamical simulations (Calura et al 2019;Yaghoobi et al 2022). The growth of a central BH to masses up to ∼10 4 M had been modeled in this context by Vesperini et al (2010), considering only sub-Eddington or Eddington accretion rates on a relative low-mass seed BH (∼100 M ) possibly produced by early stellar mergers.…”

Section: Timings Involved: Central Black Holementioning

confidence: 99%

GN-z11: Witnessing the formation of second-generation stars and an accreting massive black hole in a massive star cluster

D’Antona,

Vesperini,

Calura

et al. 2023

A&A

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We explore the possibility of the N-rich young proto-galaxy GN-z11, recently observed at z = 10.6 by JWST, being the result of the formation of second generation stars from pristine gas and asymptotic giant branch (AGB) ejecta in a massive globular cluster or nuclear star cluster. We show that a second generation forming out of gas polluted by the ejecta of massive AGB stars and mixed with gas of a standard composition accounts for the unusually large N/O in the GN-z11 spectrum. The timing of the evolution of massive (4–7.5 M⊙) AGBs also provides a favorable environment for the growth of a central stellar mass black hole to the AGN stage observed in GN-z11. According to our model, the progenitor system was born when the age of the Universe was ≃260 − 380 Myr, well within the bounds of the pre-reionization epoch.

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Section: Timings Involved: Central Black Holementioning

confidence: 99%

GN-z11: Witnessing the formation of second-generation stars and an accreting massive black hole in a massive star cluster

D’Antona,

Vesperini,

Calura

et al. 2023

A&A

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The structural properties of multiple populations in globular clusters: The instructive case of NGC 3201

Cadelano,

Dalessandro,

Vesperini

2024

A&A

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All multiple population (MP) formation models in globular clusters (GCs) predict that second population (SP) stars form more centrally concentrated than the first population (FP). As dynamical evolution proceeds, spatial differences are progressively erased and only dynamically young clusters are expected to retain a partial memory of the initial structural differences. In recent years, this picture has been supported by observations of the MP radial distributions of both Galactic and extragalactic GCs. However, more recent observations have suggested that in some systems, FPs might actually form more centrally segregated, with NGC 3201 being one significant example of such a possibility. Here, we present a detailed morphological and kinematic characterization of the MPs in NGC 3201, based on a combination of photometric and astrometric data. We show that the distribution of the SP is clearly bimodal. Specifically, the SP is significantly more centrally concentrated than the FP within $ cluster’s half-mass radius. Beyond this point, the SP fraction increases again, likely due to asymmetries in the spatial distributions of the two populations. The central concentration of the SP observed in the central regions implies that it formed more centrally concentrated than the FP, even more so than what is observed in the present-day. This interpretation is supported by the key information provided by the MP kinematic properties. Indeed, we find that the FP is isotropic across all the sampled cluster extension, while the velocity distribution of the SP becomes radially anisotropic in the cluster’s outer regions, as expected for the dynamical evolution of SP stars formed more centrally concentrated than the FP. The combination of spatial and kinematic observations provide key insights into the dynamical properties of this cluster and lend further support to scenarios in which the SP forms more centrally concentrated than the FP.

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Accretion of substellar companions as the origin of chemical abundance inhomogeneities in globular clusters

Winter

Clarke

2023

Monthly Notices of the Royal Astronomical Society

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Globular clusters exhibit abundance variations, defining ‘multiple populations’, which have prompted a protracted search for their origin. Properties requiring explanation include: the high fraction of polluted stars (∼40 − 90 percent, correlated with cluster mass), the absence of pollution in young clusters and the lower pollution rate with binarity and distance from the cluster centre. We present a novel mechanism for late delivery of pollutants into stars via accretion of sub-stellar companions. In this scenario, stars move through a medium polluted with AGB and massive star ejecta, accreting material to produce companions with typical mass ratio q ∼ 0.1. These companions undergo eccentricity excitation due to dynamical perturbations by passing stars, culminating in a merger with their host star. The accretion of the companion alters surface abundances via injected pollutant. Alongside other self-enrichment models, the companion accretion model can explain the dilution of pollutant and correlation with intra-cluster location. The model also explains the ubiquity and discreteness of the populations and correlations of enrichment rates with cluster mass, cluster age and stellar binarity. Abundance variations in some clusters can be broadly reproduced using AGB and massive binary ejecta abundances from the literature. In other clusters, some high companion mass ratios (q ≳ 1) are required. In these cases, the available mass budget necessitates a variable degree of mixing of the polluted material with the primary star, deviations from model ejecta abundances or mixing of internal burning products. We highlight the avenues of further investigation which are required to explore some of the key processes invoked in this model.

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Ionizing feedback effects on star formation in globular clusters with multiple stellar populations

Cited by 4 publications

References 76 publications

GN-z11: Witnessing the formation of second-generation stars and an accreting massive black hole in a massive star cluster

GN-z11: Witnessing the formation of second-generation stars and an accreting massive black hole in a massive star cluster

The structural properties of multiple populations in globular clusters: The instructive case of NGC 3201

Accretion of substellar companions as the origin of chemical abundance inhomogeneities in globular clusters

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