矮星系的Hα比角动量
The H$α$ specific angular momentum of dwarf galaxies
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中文总结 AI 辅助
本研究通过SHαDE巡天观测和IllustrisTNG模拟，证实矮星系与大质量盘状星系遵循相同的$j_*$-$M_*$关系，该关系在5个数量级质量范围成立，且$\alpha$存在红移依赖性。
中文摘要 AI 辅助
星系的比角动量$j$与其质量$M$的关系可表示为$j \propto M^\alpha$，被称为Fall关系，是反映星系关键物理和形态特性的基本标度关系。该关系已在质量大于$10^9 M_{\odot}$的星系中得到充分研究，但对于低质量矮星系，尤其是考虑到它们多样的形态，该关系是否成立仍不确定。本研究使用SHαDE巡天中49个恒星形成矮星系的Hα观测数据，以及20个大质量“对照”星系，研究恒星$j_*$-$M_*$关系直至质量低于$10^6 M_{\odot}$的范围。我们发现，恒星形成矮星系与大质量盘状星系遵循相同的$j_*$-$M_*$关系，其中$\alpha = 0.53 \pm 0.4$，证明该关系在5个数量级的质量范围内成立。随后，我们从IllustrisTNG宇宙学模拟中选取匹配样本，创建类似SHαDE巡天的模拟观测，发现模拟矮星系群体遵循外推的$j_*$-$M_*$关系，且向低$j_*$值方向出现扁平化和显著离散。通过追踪这些星系的演化，我们发现矮星系随时间逐渐损失$j_*$，而大质量星系在达到稳定状态前会出现$j_*$的突然跃升，这种动力学演化导致$\alpha$存在红移依赖性：在$z=2$时$\alpha=0.45$，在$z=0$时$\alpha=0.55$。尽管当前$j_*$-$M_*$关系在宽质量范围内看似简单，但形成该关系的$j$演化过程复杂且动态。
英文摘要
The relationship between a galaxy's specific angular momentum $j$ and its mass $M$, parameterised by $j \propto M^α$ and known as the Fall relation, has emerged as a fundamental scaling relation reflecting key physical and morphological properties of galaxies. This relation has been well studied for galaxies with masses above $10^{9}$ $M_{\odot}$. However, whether or not it holds for the low-mass dwarf galaxies, especially given their varied morphologies, remains uncertain. Here we use H$α$ observations of 49 star-forming dwarf galaxies from the SH$α$DE survey, as well as 20 high-mass `control' galaxies, to investigate the stellar $j_{*}$-$M_{*}$ relation down to masses below $10^{6}$ M$_{\odot}$. We find that the star-forming dwarf galaxies follow the same $j_{*}$-$M_{*}$ relation as high-mass disk-like galaxies, with $α= 0.53 \pm{0.4}$, demonstrating that the relation holds across 5 orders of magnitude in mass. We then select a matching sample from the IllustrisTNG cosmological simulation and create mock observations resembling the SH$α$DE survey. We find that the simulated dwarf galaxy population follows the extrapolated $j_{*}$-$M_{*}$ relation with a flattening and significant scatter towards lower $j_{*}$ values. Following the evolution of these galaxies, we find that dwarf galaxies experience a gradual loss in $j_{*}$ with time, while high-mass galaxies experience a sudden jump in $j_{*}$ before settling into a stable state. This dynamical evolution leads to a redshift dependence in $α$, with $α= 0.45$ at $z = 2$ and 0.55 at $z = 0$. Despite the apparent simplicity in the present-day $j_{*}$-$M_{*}$ relation over a wide mass range, the evolution of $j$ leading to this relation is complex and dynamic.
