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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2502.09710 |
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| _version_ | 1866908391763345408 |
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| author | Yuan, Zhen Matsuno, Tadafumi Sitnova, Tatyana Martin, Nicolas F. Ibata, Rodrigo A. Ardern-Arentsen, Anke Carlberg, Raymond Hernandez, Jonay I. Gonzalez Holmbeck, Erika Kordopatis, Georges Jiang, Fangzhou Malhan, Khyati Navarro, Julio Sestito, Federico Venn, Kim A. Viswanathan, Akshara Vitali, Sara |
| author_facet | Yuan, Zhen Matsuno, Tadafumi Sitnova, Tatyana Martin, Nicolas F. Ibata, Rodrigo A. Ardern-Arentsen, Anke Carlberg, Raymond Hernandez, Jonay I. Gonzalez Holmbeck, Erika Kordopatis, Georges Jiang, Fangzhou Malhan, Khyati Navarro, Julio Sestito, Federico Venn, Kim A. Viswanathan, Akshara Vitali, Sara |
| contents | The discovery of the most metal-poor stream, C-19, provides us with a fossil record of a stellar structure born very soon after the Big Bang. In this work, we search for new C-19 members over the whole sky by combining two complementary stream-searching algorithms, STREAMFINDER and StarGO,, and utilizing low-metallicity star samples from the Pristine survey as well as Gaia BP/RP spectro-photometric catalogues. We confirm twelve new members, spread over more than 100$^\circ$, using velocity and metallicity information from a set of spectroscopic follow-up programs that targeted a quasi-complete sample of our bright candidates ($G \lesssim 16.0$). From the updated set of stream members, we confirm that the stream is wide, with a stream width of $\sim200$ pc, and dynamically hot, with a derived velocity dispersion of $10.9^{+2.1}_{-1.5}$ km/s. The tension remains between these quantities and a purely baryonic scenario in which the relatively low-mass stream (even updated to a few $10^4M_{\odot}$) stems from a globular cluster progenitor, as suggested by its chemical abundances. Some heating mechanism, such as preheating of the cluster in its own dark matter halo or through interactions with halo sub-structures appears necessary to explain the tension. The impact of binaries on the measured dispersion also remains unknown. Detailed elemental abundances of more stream members as well as multi-epoch radial velocities from spectroscopic observations are therefore crucial to fully understand the nature and past history of the most metal-poor stream of the Milky Way. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_09710 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Pristine survey: XXVII. The extremely metal-poor stream C-19 stretches over more than 100 degrees Yuan, Zhen Matsuno, Tadafumi Sitnova, Tatyana Martin, Nicolas F. Ibata, Rodrigo A. Ardern-Arentsen, Anke Carlberg, Raymond Hernandez, Jonay I. Gonzalez Holmbeck, Erika Kordopatis, Georges Jiang, Fangzhou Malhan, Khyati Navarro, Julio Sestito, Federico Venn, Kim A. Viswanathan, Akshara Vitali, Sara Astrophysics of Galaxies The discovery of the most metal-poor stream, C-19, provides us with a fossil record of a stellar structure born very soon after the Big Bang. In this work, we search for new C-19 members over the whole sky by combining two complementary stream-searching algorithms, STREAMFINDER and StarGO,, and utilizing low-metallicity star samples from the Pristine survey as well as Gaia BP/RP spectro-photometric catalogues. We confirm twelve new members, spread over more than 100$^\circ$, using velocity and metallicity information from a set of spectroscopic follow-up programs that targeted a quasi-complete sample of our bright candidates ($G \lesssim 16.0$). From the updated set of stream members, we confirm that the stream is wide, with a stream width of $\sim200$ pc, and dynamically hot, with a derived velocity dispersion of $10.9^{+2.1}_{-1.5}$ km/s. The tension remains between these quantities and a purely baryonic scenario in which the relatively low-mass stream (even updated to a few $10^4M_{\odot}$) stems from a globular cluster progenitor, as suggested by its chemical abundances. Some heating mechanism, such as preheating of the cluster in its own dark matter halo or through interactions with halo sub-structures appears necessary to explain the tension. The impact of binaries on the measured dispersion also remains unknown. Detailed elemental abundances of more stream members as well as multi-epoch radial velocities from spectroscopic observations are therefore crucial to fully understand the nature and past history of the most metal-poor stream of the Milky Way. |
| title | The Pristine survey: XXVII. The extremely metal-poor stream C-19 stretches over more than 100 degrees |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2502.09710 |