Discovery of new retrograde substructures: the shards of ω Centauri?

Myeong, G. C.; Evans, N. W.; Belokurov, Vasily; Sanders, Jason L.; Koposov, S. E.

doi:10.1093/mnras/sty1403

Cited by 101 publications

(129 citation statements)

References 63 publications

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“…This subtlety is a key difference between this list and that of Ref. [12]. Accounting for multiple wraps prevents us overestimating the velocity dispersions of the objects which could be anomalously large otherwise.…”

Section: Cand14 Cand14mentioning

confidence: 93%

“…The 30 highest significance objects were initially listed in Ref. [12]; however the list in fact extends to a total of 69. We call all these objects "Shards" throughout our paper.…”

Section: B the Shardsmentioning

confidence: 99%

“…We now extend the naming convention of Ref. [12] to indicate those TABLE II. Basic parameters of the Shards.…”

Section: Cand14 Cand14mentioning

confidence: 99%

“…In terms of stellar content, two of the most substantial Shards are the S1 and S2 streams [12,26]. Modelling suggests that their progenitors had virial masses ≈ 10 10 M and stellar masses ≈ 10 6 M , comparable to modern day dwarf spheroidal satellites like Draco and Ursa Minor.…”

Section: Introductionmentioning

confidence: 99%

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Velocity substructure from Gaia and direct searches for dark matter

et al. 2020

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Data from the Gaia satellite show that the solar neighbourhood of the Milky Way's stellar halo is imprinted with substructure from several accretion events. Evidence of these events is found in "the Shards", stars clustering with high significance in both action space and metallicity. Stars in the Shards share a common origin, likely as ancient satellite galaxies of the Milky Way, so will be embedded in dark matter (DM) counterparts. These "Dark Shards" contain two substantial streams (S1 and S2), as well as several retrograde, prograde and lower energy objects. The retrograde stream S1 has a very high Earth-frame speed of ∼ 550 km s −1 while S2 moves on a prograde, but highly polar orbit and enhances peak of the speed distribution at around 300 km s −1 . The presence of the Dark Shards locally leads to modifications of many to the fundamental properties of experimental DM signals. The S2 stream in particular gives rise to an array of effects in searches for axions and in the time dependence of nuclear recoils: shifting the peak day, inducing non-sinusoidal distortions, and increasing the importance of the gravitational focusing of DM by the Sun. Dark Shards additionally bring new features for directional signals, while also enhancing the DM flux towards Cygnus.

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Section: Cand14 Cand14mentioning

confidence: 93%

“…The 30 highest significance objects were initially listed in Ref. [12]; however the list in fact extends to a total of 69. We call all these objects "Shards" throughout our paper.…”

Section: B the Shardsmentioning

confidence: 99%

“…We now extend the naming convention of Ref. [12] to indicate those TABLE II. Basic parameters of the Shards.…”

Section: Cand14 Cand14mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Velocity substructure from Gaia and direct searches for dark matter

et al. 2020

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“…Both of these works warrant follow-up in light of the new precision proper motions from Gaia. Myeong et al (2018) identified retrograde substructures in the halo based upon clustering in action space, and some of these structures they associated with ω Cen.…”

Section: Introductionmentioning

confidence: 99%

The GALAH Survey: Chemically tagging the Fimbulthul stream to the globular cluster ω Centauri

Simpson

Martell

Costa

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Using kinematics from Gaia and the large elemental abundance space of the second data release of the GALAH survey, we identify two new members of the Fimbulthul stellar stream, and chemically tag them to massive, multi-metallic globular cluster ω Centauri. Recent analysis of the second data release of Gaia had revealed the Fimbulthul stellar stream in the halo of the Milky Way. It had been proposed that the stream is associated with the ω Cen, but this proposition relied exclusively upon the kinematics and metallicities of the stars to make the association. In this work, we find our two new members of the stream to be metal-poor stars that are enhanced in sodium and aluminium, typical of second population globular cluster stars, but not otherwise seen in field stars. Furthermore, the stars share the s-process abundance pattern seen in ω Cen, which is rare in field stars. Apart from one star within 1.5 deg of ω Cen, we find no other stars observed by GALAH spatially near ω Cen or the Fimbulthul stream that could be kinematically and chemically linked to the cluster. Chemically tagging stars in the Fimbulthul stream to ω Cen confirms the earlier work, and further links this tidal feature in the Milky Way halo to ω Cen.

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Dark matter substructures affect dark matter-electron scattering in xenon-based direct detection experiments

Maity

Laha

2023

J. High Energ. Phys.

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Recent sky surveys have discovered a large number of stellar substructures. It is highly likely that there are dark matter (DM) counterparts to these stellar substructures. We examine the implications of DM substructures for electron recoil (ER) direct detection (DD) rates in dual phase xenon experiments. We have utilized the results of the LAMOST survey and considered a few benchmark substructures in our analysis. Assuming that these substructures constitute 10% of the local DM density, we study the discovery limits of DM-electron scattering cross sections considering one kg-year exposure and 1, 2, and 3 electron thresholds. With this exposure and threshold, it is possible to observe the effect of the considered DM substructure for the currently allowed parameter space. We also explore the sensitivity of these experiments in resolving the DM substructure fraction. For all the considered cases, we observe that DM having mass $$ \mathcal{O}(10) $$ O 10 MeV has a better prospect in resolving substructure fraction as compared to $$ \mathcal{O}(100) $$ O 100 MeV scale DM. We also find that within the currently allowed DM-electron scattering cross-section; these experiments can resolve the substructure fraction (provided it has a non-negligible contribution to the local DM density) with good accuracy for $$ \mathcal{O}(10) $$ O 10 MeV DM mass with one electron threshold.

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Discovery of new retrograde substructures: the shards of ω Centauri?

Cited by 101 publications

References 63 publications

Velocity substructure from Gaia and direct searches for dark matter

Velocity substructure from Gaia and direct searches for dark matter

The GALAH Survey: Chemically tagging the Fimbulthul stream to the globular cluster ω Centauri

Dark matter substructures affect dark matter-electron scattering in xenon-based direct detection experiments

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