LYRA：矮星系中核星团的形成与增长
LYRA: The formation and growth of nuclear star clusters in dwarf galaxies
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中文总结 AI 辅助
利用LYRA宇宙学模拟研究六个矮星系中核星团的形成与增长，发现其早期形成且质量主要来自原位恒星形成，并受星系并合显著影响。
中文摘要 AI 辅助
核星团（NSCs）是密集的大质量星团，普遍存在于各种质量区间的星系中心，在恒星质量 $M_\star<10^{7}\\, \mathrm{M}_\odot$ 的矮星系中，多达约30%的星系拥有核星团。尽管它们的主要增长途径已被充分研究，但其形成机制仍存在持续争论。我们利用LYRA宇宙学流体动力学模拟，研究了一个包含六个矮星系样本中核星团的形成与增长，在其中所有星系中识别出质量 $M_\mathrm{NSC} \sim 10^4 - 10^6 \\, \mathrm{M}_\odot$ 的核星团。我们样本中的核星团在早期作为致密成分出现，宿主星系围绕其增长。这与核星团是星系中最早形成的结构之一的场景一致。我们刻画了构成核星团的恒星的起源，并探索了每条通道中恒星种群的性质。我们发现，核星团的大部分质量来源于核星团自身的原位恒星形成。尽管这可能与当前观测相矛盾，但这类恒星形成的大部分发生在早期，导致存在大量年老且贫金属的恒星，这与核星团早期形成的观点相符。我们还发现星系-星系并合是核星团质量的重要贡献者，通常一次并合主导了这一贡献。我们的结果突显了矮星系中核星团增长历史的复杂性，并强调了考虑矮星系中核星团额外增长通道的重要性。
英文摘要
Nuclear star clusters (NSCs) are dense massive star clusters ubiquitous in galactic centres across various mass regimes, present in up to $\sim30$ per cent of dwarf galaxies with $M_\star<10^{7}\, \mathrm{M}_\odot$. Although their main growth pathways are well studied, there is still ongoing debate regarding their formation. We use the LYRA cosmological hydrodynamical simulations to study the formation and growth of NSCs in a sample of six dwarf galaxies, where we identify NSCs with masses $M_\mathrm{NSC} \sim 10^4 - 10^6 \, \mathrm{M}_\odot$ in all galaxies in our sample. The NSCs in our sample emerge at early times as a compact component, with the host galaxy growing around them. This is consistent with a scenario in which NSCs are among the earliest structures to form in a galaxy. We characterise the origin of the stars that constitute the NSCs and explore the properties of the stellar populations in each of these channels. We find that most of the NSC mass originates from in-situ star formation within the NSCs themselves. While this might appear at odds with current observations, the bulk of this star formation occurs at early times, resulting in a significant population of old and metal-poor stars, in agreement with an early NSC formation. We also identify galaxy-galaxy mergers as a significant contributor to the NSC mass, with usually one merger dominating this contribution. Our results highlight the complexity in the growth history of NSCs in dwarf galaxies and highlight the importance of considering additional growth channels for NSCs in dwarfs galaxies.
发表机构
- Durham University（杜伦大学）
- Stockholm University（斯德哥尔摩大学）
- European Southern Observatory（欧洲南方天文台）
- University of Hawaii（夏威夷大学）
- University of Vienna（维也纳大学）
- Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）
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