The Complexity of the Cetus Stream Unveiled from the Fusion of STREAMFINDER and StarGO

Yuan, Zhen; Malhan, Khyati; Sestito, Federico; Ibata, Rodrigo A.; Martin, Nicolas F.; Chang, Jiang; Li, Ting S.; Caffau, Elisabetta; Bonifacio, Piercarlo; Bellazzini, Michele; Huang, Yang; Voggel, Karina; Longeard, Nicolas; Arentsen, Anke; Doliva-Dolinsky, Amandine; Navarro, Julio; Famaey, Benoit; Starkenburg, Else; Aguado, David S.

doi:10.48550/arxiv.2112.05775

Cited by 5 publications

(7 citation statements)

References 99 publications

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“…The Arjuna structure identified in that work is treated here as the highly retrograde debris of GSE, and is thus included as a part of GSE (see Naidu et al 2021 for details). With the acquisition of new southern fields covering the dynamically cold Cetus stream (e.g., Newberg et al 2009;Thomas & Battaglia 2021;Yuan et al 2021), the current H3 giants sample (> 2.5× larger than the sample studied in Naidu et al 2020a) now has N = 56 confident Cetus members. Due to its dynamical coherence, Cetus is easily selected as follows:…”

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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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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“…between the cluster and Cetus stream. Furthermore, Yuan et al (2021) concentrated on searching for Cetus's members using data covering the cluster but they did not detect any densely populated structure around NGC 5824. Hence the features should not be a part of Cetus.…”

Section: Resultsmentioning

confidence: 99%

“…connection between the cluster and Cetus stream. Furthermore, Yuan et al (2021) concentrated on searching for Cetus's members using data covering the cluster but they did not detect any densely populated structure around NGC 5824, and as a result, the features should not be a part of Cetus; and (iv) Triangulum as a piece of the leading tail also provides weak evidence of existence of the trailing tail.…”

Section: Resultsmentioning

confidence: 99%

Existence of tidal tails for the globular cluster NGC 5824

Yang

Zhao

Ishigaki

et al. 2022

A&A

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Context. Several dynamically cold streams have been associated with certain globular clusters (GCs) based on orbital energies and angular momenta. Some of these streams are surprisingly far apart from their progenitors and one such pair is Triangulum and NGC 5824. Triangulum can be considered as a piece of NGC 5824 leading tail since the cluster's future orbit matches with the stream's track well. The existence of the leading tail for NGC 5824 is the motivation behind the search for its trailing tail. Aims. Our goal is to confirm the connection between Triangulum and NGC 5824 and seek the trailing tail of the cluster. Methods. The selection of member stars of Triangulum is made through various cuts in metallicity, proper motions (PMs), radial velocity and color-magnitude diagram (CMD). The selected members are compared in phase space to a mock stream which models the disruption of NGC 5824. We then try to detect the trailing tail of the cluster based on a modified matched-filter technique. Stars are assigned weights using their color differences from the cluster's locus in CMD. These weights are further scaled based on stars' departures from expected PMs of the model stream. Results. A total of 26 member stars for Triangulum are obtained and 16 of them are newly identified. These members are consistent with the mock stream in the phase space and their metalicity and position on the CMD are in good agreements with NGC 5824. By applying the matched-filter, a tenuous trailing tail of the cluster is detected, spanning ∼ 50 • long on sky. The signature matches with the mock stream's trajectory well. Conclusions. Our results support that Triangulum stream acts as a part of the leading tail for NGC 5824. On the trailing side, we have detected a 50 • tail extended from the cluster. The existence of both leading and trailing tails for the GC NGC 5824 is verified.

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“…We use star particles from five tailor-made N-body simulations, representing GSE , Sagittarius (Vasiliev et al 2021), the Helmi Streams (Koppelman et al 2019), Wukong/LMS-1 (hereafter Wukong, Malhan et al 2021), and Cetus (Yuan et al 2021). We note that for Sagittarius, we cut out the intact core and keep the remaining ≈ 3 × 10 8 M found within the disrupted tails.…”

Section: Methods 21 Simulation Sourcesmentioning

confidence: 99%

What is Missing from the Local Stellar Halo?

Sharpe¹,

Naidu²,

Conroy³

2022

Preprint

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The Milky Way's stellar halo, which extends to > 100 kpc, encodes the evolutionary history of our Galaxy. However, most studies of the halo to date have been limited to within a few kpc of the Sun. Here, we characterize differences between this local halo and the stellar halo in its entirety. We construct a composite stellar halo model by combining observationally motivated N-body simulations of the Milky Way's nine most massive disrupted dwarf galaxies that account for almost all of the mass in the halo. We find that (1) the representation by mass of different dwarf galaxies in the local halo compared to the whole halo can be significantly overestimated (e.g., the Helmi Streams) or underestimated (e.g., Cetus) and ( 2) properties of the overall halo (e.g., net rotation) inferred via orbit integration of local halo stars are significantly biased, because e.g., highly retrograde debris from Gaia-Sausage-Enceladus is missing from the local halo. Therefore, extrapolations from the local to the global halo should be treated with caution. From analysis of a sample of 11 MW-like simulated halos, we identify a population of recently accreted ( 5 Gyrs) and disrupted galaxies on high angular momenta orbits that are entirely missing from local samples, and awaiting discovery in the outer halo. Our results motivate the need for surveys of halo stars extending to the Galaxy's virial radius.

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The Complexity of the Cetus Stream Unveiled from the Fusion of STREAMFINDER and StarGO

Cited by 5 publications

References 99 publications

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

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

Existence of tidal tails for the globular cluster NGC 5824

What is Missing from the Local Stellar Halo?

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