The Pristine survey -- XVI. The metallicity of 26 stellar streams around the Milky Way detected with the STREAMFINDER in Gaia EDR3

Martín, Nicolás F.; Ibata, Rodrigo; Starkenburg, Else; Yuan, Zhen; Malhan, Khyati; Bellazzini, M.; Viswanathan, Akshara; Aguado, David Carrizo; Arentsen, Anke; Bonifacio, P.; Carlberg, R. G.; Hernández, J. I. González; Hill, V.; Jablonka, P.; Kordopatis, G.; Lardo, C.; McConnachie, Alan W.; Navarro, Julio F.; Sánchéz-Janssen, R.; Sestito, Federico; Thomas, Guillaume; Venn, Kim A.; Vitali, Sara; Voggel, Karina

doi:10.48550/arxiv.2201.01310

Cited by 5 publications

(5 citation statements)

References 75 publications

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“…One clear difference from observations is the metallicity of the clusters in our simulations, which are slightly lower than metallicities of well-quantified GCs observed in dwarf galaxies (Beasley et al 2019) and have larger iron metallicity spreads (0.15 − 0.2 dex; the metallicity distributions are reasonably well approximated by gaussians with 𝜎 = 0.15 dex across the simulation suite) than are observed (0.045 dex; Carretta et al 2009;Bailin 2019). This could be an indication that the clusters formed here would be disrupted and form the streams that are known to have lower metallicities (Martin et al 2022), or it could mean that subtle aspects of the galaxy formation modeling in FIRE require refinements in this regime. Indeed, Wheeler et al (2019) noted that low-mass dwarf galaxies from FIRE-2 lie slightly but systematically below the observed mass-metallicity relationship.…”

Section: Comparison With Previous Resultsmentioning

confidence: 52%

Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at $z>4$

Sameie¹,

Boylan-Kolchin²,

Hopkins³

et al. 2022

Preprint

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We perform cosmological hydrodynamical simulations to study the formation of proto-globular cluster candidates in progenitors of present-day dwarf galaxies (𝑀 vir ≈ 10 10 M at 𝑧 = 0) as part of the "Feedback in Realistic Environment" (FIRE) project. Compact (𝑟 1/2 < 30 pc), relatively massive (0.5 × 10 5 𝑀 ★ /M 5 × 10 5 ), self-bound stellar clusters form at 11 𝑧 5 in progenitors with 𝑀 vir ≈ 10 9 M . Cluster formation is triggered when at least 10 7 M of dense, turbulent gas reaches Σ gas ≈ 10 4 M pc −2 as a result of the compressive effects of supernova feedback or from cloud-cloud collisions. The clusters can survive for 2 − 3 Gyr; absent numerical effects, they would likely survive substantially longer, perhaps to 𝑧 = 0. The longest-lived clusters are those that form at significant distance -several hundreds of pc -from their host galaxy. We therefore predict that globular clusters forming in progenitors of present-day dwarf galaxies will be offset from any pre-existing stars within their host dark matter halos as opposed to deeply embedded within a well-defined galaxy. Properties of the nascent clusters are consistent with observations of some of the faintest and most compact high-redshift sources in Hubble Space Telescope lensing fields and are at the edge of what will be detectable as point sources in deep imaging of non-lensed fields with the James Webb Space Telescope. By contrast, the star clusters' host galaxies will remain undetectable.

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Section: Comparison With Previous Resultsmentioning

confidence: 52%

Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at $z>4$

Sameie¹,

Boylan-Kolchin²,

Hopkins³

et al. 2022

Preprint

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“…On the one hand, recently accreted dwarf galaxies are being disrupted to form stellar streams. These stellar streams have a spatially coherent structure, and they are extensively searched for by large photometric and astrometric surveys (Belokurov et al 2006;Malhan et al 2018;Shipp et al 2018;Ibata et al 2021;Martin et al 2022). To date, nearly 100 stellar streams have been found (Mateu 2023), and many of these streams are thought to be associated with large merger events (Bonaca et al 2021;Malhan et al 2022).…”

Section: Reconstructing the Galactic Merger Historymentioning

confidence: 99%

Finding r-II Sibling Stars in the Milky Way with the Greedy Optimistic Clustering Algorithm

Hattori

Okuno

Roederer

2023

ApJ

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R-process enhanced stars with [Eu/Fe] ≥ +0.7 (so-called r-II stars) are believed to have formed in an extremely neutron-rich environment in which a rare astrophysical event (e.g., a neutron-star merger) occurred. This scenario is supported by the existence of an ultra-faint dwarf galaxy, Reticulum II, where most of the stars are highly enhanced in r-process elements. In this scenario, some small fraction of dwarf galaxies around the Milky Way were r enhanced. When each r-enhanced dwarf galaxy accreted to the Milky Way, it deposited many r-II stars in the Galactic halo with similar orbital actions. To search for the remnants of the r-enhanced systems, we analyzed the distribution of the orbital actions of N = 161 r-II stars in the solar neighborhood by using Gaia EDR3 data. Since the observational uncertainty is not negligible, we applied a newly developed greedy optimistic clustering method to the orbital actions of our sample stars. We found six clusters of r-II stars that have similar orbits and chemistry, one of which is a new discovery. Given the apparent phase-mixed orbits of the member stars, we interpret that these clusters are good candidates for remnants of completely disrupted r-enhanced dwarf galaxies that merged with the ancient Milky Way.

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“…† E-mail: alexji@uchicago.edu streams are very close to the Sun, though streams initially identified just with deep photometry tend to be found at larger distances (Bonaca et al 2021;Li et al 2022;Martin et al 2022;Malhan et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Chemical Abundances of the Typhon Stellar Stream

Ji¹,

Naidu²,

Brauer³

et al. 2022

Preprint

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We present the first high-resolution chemical abundances of seven stars in the recently discovered high-energy dwarf galaxy stream Typhon. Typhon stars have apocenters reaching to 100 kpc, making this the first detailed chemical picture of the Milky Way's very distant stellar halo. Typhon's chemical abundances are more like a dwarf galaxy than a globular cluster, showing a metallicity dispersion and no presence of multiple stellar populations. We find that Typhon stars display enhanced 𝛼-element abundances and increasing 𝑟-process abundances with increasing metallicity. The high-𝛼 abundances suggest a short star formation duration for Typhon, but this is at odds with expectations for the distant Milky Way halo and the presence of delayed 𝑟-process enrichment. If the progenitor of Typhon is indeed a new dwarf galaxy, possible scenarios explaining this apparent contradiction include a dynamical interaction within the Milky Way that increases Typhon's orbital energy, a burst of enhanced late-time star formation that raises [𝛼/Fe], and/or group preprocessing by another dwarf galaxy before infall into the Milky Way. An alternate explanation is that Typhon is the high-energy tail of a more massive disrupted dwarf galaxy that lost energy through dynamical friction. We cannot clearly identify a known low-energy progenitor of Typhon, but cosmological simulations give about 2:1 odds that Typhon is a high-energy tail of a massive galaxy instead of a new disrupted galaxy. Typhon's surprising combination of kinematics and chemistry thus underscores the need to fully characterize the dynamical history and detailed abundances of known substructures before identifying the origin of new substructures.

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The Pristine survey -- XVI. The metallicity of 26 stellar streams around the Milky Way detected with the STREAMFINDER in Gaia EDR3

Cited by 5 publications

References 75 publications

Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at $z>4$

Formation of proto-globular cluster candidates in cosmological simulations of dwarf galaxies at $z>4$

Finding r-II Sibling Stars in the Milky Way with the Greedy Optimistic Clustering Algorithm

Chemical Abundances of the Typhon Stellar Stream

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