The chemo-dynamical groups of Galactic globular clusters

Callingham, Thomas M.; Cautun, Marius; Deason, Alis J.; Frenk, Carlos S.; Grand, Robert J. J.; Marinacci, Federico

doi:10.1093/mnras/stac1145

Cited by 51 publications

(33 citation statements)

References 117 publications

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“…11 The mass of this GC translates into M å host galaxy ≈ 1.3 × 10 9 M e for its former host galaxy. Such M å value is well within the literature range for GSE (see Figure 6) and is more than 10 times larger than the expected value for Sequoia of ∼5-8 × 10 7 M e (Myeong et al 2019;Forbes 2020;Kruijssen et al 2020;Callingham et al 2022). Following this line of thought, it would be natural to imagine GSE as a stronger candidate as the host of such a robust NSC.…”

Section: The Case Of ωCen and Ngc 1851supporting

confidence: 82%

“…These authors demonstrated that GCs of GSE, selected from dynamics alone, follow a track in AMR clearly separated from their in situ counterparts, being more metal-poor within the same age interval (data from Forbes & Bridges 2010). These results were confirmed and expanded with new DRs from Gaia by many subsequent studies (Massari et al 2019;Forbes 2020;Horta et al 2020;Kruijssen et al 2020;Callingham et al 2022).…”

Section: Candidates In the Literaturesupporting

confidence: 61%

“…However, Pfeffer et al (2021) performed a critical assessment of such claims and concluded that NGC 1851 is not a strong candidate for a NSC due its metallicity spread being so small and still contested; Villanova et al (2010) found no evidence for an intrinsic [Fe/H] dispersion within the uncertainties. Recently, Callingham et al (2022) used all available information (dynamics+metallicities +ages; Kruijssen et al 2019b) to classify Galactic GCs and found an almost certain GSE membership for ωCen.…”

Section: The Case Of ωCen and Ngc 1851mentioning

confidence: 99%

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Reconstructing the Disrupted Dwarf Galaxy Gaia-Sausage/Enceladus Using Its Stars and Globular Clusters

Limberg¹,

Souza

Pérez-Villegas

et al. 2022

ApJ

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We combine spectroscopic, photometric, and astrometric information from APOGEE data release 17 and Gaia early data release 3 to perform a self-consistent characterization of Gaia-Sausage/Enceladus (GSE), the remnant of the last major merger experienced by the Milky Way, considering stars and globular clusters (GCs) altogether. Our novel set of chemodynamical criteria to select genuine stars of GSE yields a metallicity distribution function with a median [Fe/H] of −1.22 and 0.23 dex dispersion. Stars from GSE present an excess of [Al/Fe] and [Mg/Mn] (also [Mg/Fe]) in comparison to surviving Milky Way dwarf satellites, which can be explained by differences in star formation efficiencies and timescales between these systems. However, stars from Sequoia, another proposed accreted halo substructure, essentially overlap the GSE footprint in all analyzed chemical-abundance spaces, but present lower metallicities. Among the probable GCs of GSE with APOGEE observations available, we find no evidence for atypical [Fe/H] spreads with the exception of ω Centauri (ωCen). Under the assumption that ωCen is a stripped nuclear star cluster, we estimate the stellar mass of its progenitor to be M ⋆ ≈ 1.3 × 109 M ⊙, well within literature expectations for GSE. This leads us to envision GSE as the best available candidate for the original host galaxy of ωCen. We also take advantage of Gaia's photometry and APOGEE metallicities as priors to determine fundamental parameters for eight high-probability (>70%) GC members of GSE via statistical isochrone fitting. Finally, the newly determined ages and APOGEE [Fe/H] values are utilized to model the age–metallicity relation of GSE.

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Section: The Case Of ωCen and Ngc 1851supporting

confidence: 82%

Section: Candidates In the Literaturesupporting

confidence: 61%

Section: The Case Of ωCen and Ngc 1851mentioning

confidence: 99%

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Reconstructing the Disrupted Dwarf Galaxy Gaia-Sausage/Enceladus Using Its Stars and Globular Clusters

Limberg¹,

Souza

Pérez-Villegas

et al. 2022

ApJ

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“…Using established mass-metallicity relations (see Kirby et al 2013), the total stellar mass of the progenitor dwarf before disruption can be gleaned from the typical metallicity of its stellar population (Belokurov et al 2018;Feuillet et al 2019;Naidu et al 2021). An independent mass constraint can be obtained by scaling up the total number of GCs associated with the merger (Myeong et al 2018c(Myeong et al , 2019Massari et al 2019;Forbes 2020;Callingham et al 2022). A third method of constraining the total stellar mass is via the analysis of the GS/E chemical pattern (e.g., Fernández-Alvar et al 2018;Helmi et al 2018;Mackereth et al 2019;Vincenzo et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Milky Way's Eccentric Constituents with Gaia, APOGEE, and GALAH

Belokurov

Aguado

Evans

et al. 2022

ApJ

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We report the results of an unsupervised decomposition of the local stellar halo in the chemodynamical space spanned by the abundance measurements from APOGEE DR17 and GALAH DR3. In our Gaussian mixture model, only four independent components dominate the halo in the solar neighborhood, three previously known, Aurora, Splash, and Gaia-Sausage/Enceladus (GS/E), and one new, Eos. Only one of these four is of accreted origin, namely, the GS/E, thus supporting the earlier claims that the GS/E is the main progenitor of the Galactic stellar halo. We show that Aurora is entirely consistent with the chemical properties of the so-called Heracles merger. In our analysis in which no predefined chemical selection cuts are applied, Aurora spans a wide range of [Al/Fe] with a metallicity correlation indicative of a fast chemical enrichment in a massive galaxy, the young Milky Way. The new halo component dubbed Eos is classified as in situ given its high mean [Al/Fe]. Eos shows strong evolution as a function of [Fe/H], where it changes from being the closest to GS/E at its lowest [Fe/H] to being indistinguishable from the Galactic low-α population at its highest [Fe/H]. We surmise that at least some of the outer thin disk of the Galaxy started its evolution in the gas polluted by the GS/E, and Eos is evidence of this process.

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“…They did, however, identify three massive satellite progenitors for the ex-situ globular cluster population. This includes a galaxy dubbed "Kraken", to which they attribute 40% of ex-situ globular clusters (Kruĳssen et al 2020;Callingham et al 2022). Other techniques based on Machine Learning algorithms, such as boosted decision trees have been utilized on the scale of individual stars by Veljanoski et al (2018) to identify MW halo stars.…”

Section: Introductionmentioning

confidence: 99%

Machine Learning for Galactic Archaeology: A chemistry-based neural network method for identification of accreted disc stars

Tronrud,

Tissera,

Gómez

et al. 2022

Preprint

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We develop a method ('Galactic Archaeology Neural Network', GANN) based on neural network models (NNMs) to identify accreted stars in galactic discs by only their chemical fingerprint and age, using a suite of simulated galaxies from the Auriga Project. We train the network on the target galaxy's own local environment defined by the stellar halo and the surviving satellites. We demonstrate that this approach allows the detection of accreted stars that are spatially mixed into the disc. Two performance measures are defined -recovery fraction of accreted stars, 𝑓 recov and the probability that a star with a positive (accreted) classification is a true-positive result, 𝑃(𝑇 𝑃). As the NNM output is akin to an assigned probability (𝑃 a ), we are able to determine positivity based on flexible threshold values that can be adjusted easily to refine the selection of presumed-accreted stars. We find that GANN identifies accreted disc stars within simulated galaxies, with high 𝑓 recov and/or high 𝑃(𝑇 𝑃). We also find that stars in Gaia-Enceladus-Sausage (GES) mass systems are over 50% recovered by our NNMs in the majority (18/24) of cases. Additionally, nearly every individual source of accreted stars is detected at 10% or more of its peak stellar mass in the disc. We also demonstrate that a conglomerated NNM, trained on the halo and satellite stars from all of the Auriga galaxies provides the most consistent results, and could prove to be an intriguing future approach as our observational capabilities expand.

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The chemo-dynamical groups of Galactic globular clusters

Cited by 51 publications

References 117 publications

Reconstructing the Disrupted Dwarf Galaxy Gaia-Sausage/Enceladus Using Its Stars and Globular Clusters

Reconstructing the Disrupted Dwarf Galaxy Gaia-Sausage/Enceladus Using Its Stars and Globular Clusters

Milky Way's Eccentric Constituents with Gaia, APOGEE, and GALAH

Machine Learning for Galactic Archaeology: A chemistry-based neural network method for identification of accreted disc stars

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