The formation of cores in galaxies across cosmic time - the existence of cores is not in tension with the ?CDM paradigm
The formation of cores in galaxies across cosmic time - the existence of cores is not in tension with the ?CDM paradigm
复制标题
跨越宇宙时间的星系核心的形成 - 核心的存在与 ?CDM 范式并不冲突
DOI：
10.1093/mnras/stae056
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发表时间：
2024
影响因子：
4.8
通讯作者：
Jackson R
中科院分区：
文献类型：
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作者：
Jackson R
“核心-尖点”问题被认为是ΛCDM范式的关键挑战。暗物质中的晕只有模拟表现出“尖”的轮廓，密度不断增加的中心。然而，许多观测到的星系（特别是矮星系）的暗物质轮廓与这一预测严重偏离，中心区域（“核心”）更加平坦。我们useNewHorizon（NH），一个流体动力学宇宙学模拟，调查核心的形成，使用统计上显着数量的星系在宇宙学体积。在恒星质量分布的上端（M <$1010.2M <$）和下端（M <$≤ 108 M <$），包含星系的晕包含尖点。然而，含有中等恒星质量（108 M <$≤ M <$≤ 1010.2 M <$）的星系的晕通常是有核的，典型的晕质量在1010.2 M <$和1011.5 M <$之间。核心的形成是通过超新星驱动的气体从晕中心的移动，这改变了中心的引力势，诱导暗物质迁移到更大的半径。虽然所有大质量（M <$≥ 109.5M <$）星系都经历了核心阶段，但在某些情况下，核心可以被移除，尖点可以重新形成。如果一个星系在高红移下经历持续的星星形成，就会发生这种情况，这会导致恒星（与气体不同，不能被重子反馈移除）占据中心引力势。在宇宙星星形成高峰之后，核心的数量和它们形成的晕的质量保持不变，这表明核心在达到阈值晕质量之后在宇宙时间内常规地形成。因此，核心的存在与标准范式并不矛盾。
The ‘core-cusp’ problem is considered a key challenge to the ΛCDM paradigm. Haloes in dark matter only simulations exhibit ‘cuspy’ profiles, where density continuously increases towards the centre. However, the dark matter profiles of many observed galaxies (particularly in the dwarf regime) deviate strongly from this prediction, with much flatter central regions (‘cores’). We useNewHorizon(NH), a hydrodynamical cosmological simulation, to investigate core formation, using a statistically significant number of galaxies in a cosmological volume. Haloes containing galaxies in the upper (M⋆≥ 1010.2M⊙) and lower (M⋆≤ 108M⊙) ends of the stellar mass distribution contain cusps. However, Haloes containing galaxies with intermediate (108M⊙≤ M⋆≤ 1010.2M⊙) stellar masses are generally cored, with typical halo masses between 1010.2M⊙and 1011.5M⊙. Cores form through supernova-driven gas removal from halo centres, which alters the central gravitational potential, inducing dark matter to migrate to larger radii. While all massive (M⋆≥ 109.5M⊙) galaxies undergo a cored-phase, in some cases cores can be removed and cusps reformed. This happens if a galaxy undergoes sustained star formation at high redshift, which results in stars (which, unlike the gas, cannot be removed by baryonic feedback) dominating the central gravitational potential. After cosmic star formation peaks, the number of cores, and the mass of the Haloes they are formed in, remain constant, indicating that cores are being routinely formed over cosmic time after a threshold halo mass is reached. The existence of cores is, therefore, not in tension with the standard paradigm.