Real and counterfeit cores: how feedback expands haloes and disrupts tracers of inner gravitational potential in dwarf galaxies
Real and counterfeit cores: how feedback expands haloes and disrupts tracers of inner gravitational potential in dwarf galaxies
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真实和伪造的核心：反馈如何扩大光环并扰乱矮星系中内部引力势的示踪剂
DOI：
10.1093/mnras/stad109
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发表时间：
2023
影响因子：
4.8
通讯作者：
Burger, Jan D.
中科院分区：
文献类型：
--
作者：
Jahn, Ethan D.;Sales, Laura V.;Marinacci, Federico;Vogelsberger, Mark;Torrey, Paul;Qi, Jia;Smith, Aaron;Li, Hui;Kannan, Rahul;Burger, Jan D.
Lambda冷暗物质模拟中的发散密度分布与观测星系的恒定密度内部区域之间的紧张关系是一个长期存在的挑战，称为“核心尖点”问题。我们证明了在大气运动网格程序中实现的SMUGGLE星系形成模型在M200 × 1010 Msun的初始尖状暗物质晕的M200 × 1010 Msun的理想化矮星系中形成了恒定密度的核心。相同的初始条件运行一个有效的状态方程星际介质模型保持尖。有关这一主题的文献指出，在这些有效的模型中，星星形成的低密度阈值ρth是重子诱导核心形成的障碍。使用具有相同ρth的SMUGGLErun，我们证明了核心的形成可以在低密度阈值下进行，这表明ρ th本身不足以确定星系是否形成核心。我们重申，能够解决一个多相星际介质在足够高的密度是一个更可靠的指标核心形成比任何个别的模型参数。在SMUGGLE中，核心的形成伴随着大程度的非圆周运动，气体旋转速度剖面始终低于圆周速度，达到10.2 kpc。不对称漂移校正有助于恢复我们的一些效率较低的反馈运行的平均潜在DM潜力，但在瞬时方位角气体速度分量的时间变化是巨大的，突出了需要仔细建模的内部区域的矮星，以推断DM的真实分布。
The tension between the diverging density profiles in Lambda cold dark matter simulations and the constant-density inner regions of observed galaxies is a long-standing challenge known as the ‘core–cusp’ problem. We demonstrate that theSMUGGLEgalaxy formation model implemented in thearepomoving mesh code forms constant-density cores in idealized dwarf galaxies ofM⋆≈ 8 × 107Msunwith initially cuspy dark matter (DM) haloes ofM200≈ 1010Msun. Identical initial conditions run with an effective equation of state interstellar medium model preserve cuspiness. Literature on the subject has pointed to the low density threshold for star formation, ρth, in such effective models as an obstacle to baryon-induced core formation. Using aSMUGGLErun with equal ρth, we demonstrate that core formation can proceed at low density thresholds, indicating that ρthis insufficient on its own to determine whether a galaxy develops a core. We reaffirm that the ability to resolve a multiphase interstellar medium at sufficiently high densities is a more reliable indicator of core formation than any individual model parameter. InSMUGGLE, core formation is accompanied by large degrees of non-circular motion, with gas rotational velocity profiles that consistently fall below the circular velocityout to ∼2 kpc. Asymmetric drift corrections help recover the average underlying DM potential for some of our less efficient feedback runs, but time-variations in the instantaneous azimuthal gas velocity component are substantial, highlighting the need for careful modelling in the inner regions of dwarfs to infer the true distribution of DM.