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:10.48550/arxiv.2202.00591

Cited by 4 publications

(10 citation statements)

References 85 publications

(130 reference statements)

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“…The mass of this GC translates into M host galaxy ≈ 1.3 × 10 9 M for its former host galaxy. Such M 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 (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 a intrinsic [Fe/H] dispersion within 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,

Souza²,

Pérez-Villegas³

et al. 2022

Preprint

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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 dex 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 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 × 10 9 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 highprobability (>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,

Souza²,

Pérez-Villegas³

et al. 2022

Preprint

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“…For instance, Wukong's star counts are ≈ 2.5% of those of GSE, and so we infer its mass is ≈ 1.3 × 10 7 M . We choose GSE as the reference object to derive other systems' masses because its stellar mass has been estimated via multiple independent methods that agree well with each other (e.g., Helmi et al 2018;Kruijssen et al 2020;Mackereth & Bovy 2020;Naidu et al 2021;Callingham et al 2022), and because it is fairly well mixed within the H3 Survey footprint (Han et al 2022). As a sanity check, based on this method, Sgr would have an inferred stellar mass of ≈ 3 × 10 8 M , which is in excellent agreement with various literature estimates that span ≈ 2 − 6 × 10 8 M (e.g., Niederste-Ostholt et al 2010;Law & Majewski 2010;Kruijssen et al 2020;Vasiliev & Belokurov 2020), and within a factor of 2 of our adopted value (6 × 10 8 M ) from Laporte et al 2018.…”

Section: Disrupted Galaxy Samplementioning

confidence: 99%

Live Fast, Die $α$-Enhanced: The Mass-Metallicity-$α$ Relation of the Milky Way's Disrupted Dwarf Galaxies

Naidu¹,

Conroy²,

Bonaca³

et al. 2022

Preprint

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The Milky Way's satellite galaxies ("surviving dwarfs") have been studied for decades as unique probes of chemical evolution in the low-mass regime. Here we extend such studies to the "disrupted dwarfs", whose debris constitutes the stellar halo. We present abundances ([Fe/H], [α/Fe]) and stellar masses for nine disrupted dwarfs with M ≈ 10 6 − 10 9 M from the H3 Survey (Sagittarius, Gaia-Sausage-Enceladus, Helmi Streams, Sequoia, Wukong/LMS-1, Cetus, Thamnos, I'itoi, Orphan/Chenab). The surviving and disrupted dwarfs are chemically distinct: at fixed mass, the disrupted dwarfs are systematically metal-poor and α-enhanced. The disrupted dwarfs define a massmetallicity relation (MZR) with a similar slope as the z = 0 MZR followed by the surviving dwarfs, but offset to lower metallicities by ∆[Fe/H]≈0.3−0.4 dex. Dwarfs with larger offsets from the z = 0 MZR are more α-enhanced with [α/Fe] = 0.43 +0.09 −0.09 × ∆[Fe/H] + 0.08 +0.03 −0.03 . In simulations as well as observations, galaxies with higher ∆[Fe/H] formed at higher redshifts -exploiting this, we infer the disrupted dwarfs have typical star-formation truncation redshifts of z trunc ∼1 − 2. We compare the chemically inferred z trunc with dynamically inferred accretion redshifts and find almost all dwarfs are quenched only after accretion. The differences between disrupted and surviving dwarfs are likely because the disrupted dwarfs assembled their mass rapidly, at higher redshifts, and within denser dark matter halos that formed closer to the Galaxy. Our results place novel archaeological constraints on low-mass galaxies inaccessible to direct high-z studies: (i) the redshift evolution of the MZR along parallel tracks but offset to lower metallicities extends to M ≈ 10 6 − 10 9 M ; (ii) galaxies at z ≈ 2 − 3 are α-enhanced with [α/Fe]≈0.4.

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“…Recent studies (Trujillo-Gomez et al 2021;Wu et al 2021;Callingham et al 2022) focusing on the kinematics of GCs and halo stars have shown that orbital actions and integral of motions are useful probes of the dynamical histories of galaxies. These quantities are generally conserved during the slow evolution of the gravitational potential (Binney & Tremaine 2008).…”

Section: Orbital Actionsmentioning

confidence: 99%

Modeling the kinematics of globular cluster systems

Chen,

Gnedin

2022

Preprint

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Globular clusters (GCs) are old massive star clusters that serve as 'fossils' of galaxy formation. The advent of Gaia observatory has enabled kinematics studies of the Galactic GCs with great detail and revolutionized our understanding of the connections between GC properties and galaxy assembly. However, lack of kinematic measurements of extragalactic GCs limits the sample size of GC systems that we can fully study observationally. In this work, we present a model for GC formation and evolution, which includes positional and kinematic information of individual GCs by assigning them to particles in the Illustris TNG50-1 simulation based on the age and location. The model predictions are consistent with many observed properties of GC systems, including the distributions of position, systemic velocity, velocity dispersion, anisotropy parameter, orbital actions, and metallicities. We also analyze the properties of GCs from different origins. In the outer galaxy, ex-situ clusters are more dominant than the clusters formed in-situ. This leads to the GC metallicities decreasing outwards due to the increasing abundance of accreted, metal-poor clusters. We also find the ex-situ GCs to have greater velocity dispersions and orbital actions, in agreement with their accretion origin.

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The Chemo-Dynamical Groups of Galactic Globular Clusters

Cited by 4 publications

References 85 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

Live Fast, Die $α$-Enhanced: The Mass-Metallicity-$α$ Relation of the Milky Way's Disrupted Dwarf Galaxies

Modeling the kinematics of globular cluster systems

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