论文标题
H3调查的证据表明，恒星光环完全由子结构组成
Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
论文作者
论文摘要
在$λ$ CDM范式中，银河恒星光环预计将携带较小系统的吸收碎片。为了识别这些系统，H3光谱调查与$ GAIA $相结合，正在遥远的银河系中收集6D相位空间和化学信息。在这里，我们使用$ | b |> 40^{\ circ} $和$ | z |> 2 $ kpc的5684个巨人的样本在50 kpc内列出了50 kpc的综合结构清单。我们确定已知的结构，包括高$α$磁盘，原位光环（磁盘恒星加热到怪异轨道），射手座（SGR），$ gaia $ -sausage-enceladus（GSE），helmi流，红杉，红杉和thamnos。 Additionally, we identify the following new structures: (i) Aleph ([Fe/H]$=-0.5$), a low eccentricity structure that rises a surprising 10 kpc off the plane, (ii, iii) Arjuna ([Fe/H]$=-1.2$) and I'itoi ([Fe/H]$<-2$), which comprise the high-energy retrograde halo along with Sequoia, and (iv) Wukong（[Fe/h] $ = -1.6 $），这是一个与GSE化学不同的序列相位密度。对于每个结构，我们提供[Fe/H]，[$α$/Fe]和轨道参数。星系中出生的星星是$ | z | \ sim $ 2 kpc（$ \ $ \ $ 60 $ \％$）的主要组成部分，但它们的相对分数急剧下降至$ \ lessim $ 5 $ \％$ \％$ \％$ \％$ \％$ \％$ \％。超过15 kpc，$> $ 80 $ \％$ $ \％$由两个巨大（$ m _ {\ star} \ sim10^{8} {8} -10^{9} m _ {\ odot} $添加到25 kse（fe/h] $ = - 1.2 $）25 kpc，和sgr（SGR），以及SGR（$） KPC。这解释了光环（[Fe/H] $ \ \ 1.2 $）相对较高的总体金属性。我们将样本的$ \ gtrsim $ \ gtrsim归因于列出的一个结构之一，指的是完全由积聚矮人和磁盘加热的光环。
In the $Λ$CDM paradigm the Galactic stellar halo is predicted to harbor the accreted debris of smaller systems. To identify these systems, the H3 Spectroscopic Survey, combined with $Gaia$, is gathering 6D phase-space and chemical information in the distant Galaxy. Here we present a comprehensive inventory of structure within 50 kpc from the Galactic center using a sample of 5684 giants at $|b|>40^{\circ}$ and $|Z|>2$ kpc. We identify known structures including the high-$α$ disk, the in-situ halo (disk stars heated to eccentric orbits), Sagittarius (Sgr), $Gaia$-Sausage-Enceladus (GSE), the Helmi Streams, Sequoia, and Thamnos. Additionally, we identify the following new structures: (i) Aleph ([Fe/H]$=-0.5$), a low eccentricity structure that rises a surprising 10 kpc off the plane, (ii, iii) Arjuna ([Fe/H]$=-1.2$) and I'itoi ([Fe/H]$<-2$), which comprise the high-energy retrograde halo along with Sequoia, and (iv) Wukong ([Fe/H]$=-1.6$), a prograde phase-space overdensity chemically distinct from GSE. For each structure we provide [Fe/H], [$α$/Fe], and orbital parameters. Stars born within the Galaxy are a major component at $|Z|\sim$2 kpc ($\approx$60$\%$), but their relative fraction declines sharply to $\lesssim$5$\%$ past 15 kpc. Beyond 15 kpc, $>$80$\%$ of the halo is built by two massive ($M_{\star}\sim10^{8}-10^{9}M_{\odot}$) accreted dwarfs: GSE ([Fe/H]$=-1.2$) within 25 kpc, and Sgr ([Fe/H]$=-1.0$) beyond 25 kpc. This explains the relatively high overall metallicity of the halo ([Fe/H]$\approx-1.2$). We attribute $\gtrsim$95$\%$ of the sample to one of the listed structures, pointing to a halo built entirely from accreted dwarfs and heating of the disk.
