The Milky Way tomography with APOGEE: intrinsic density distribution and structure of mono-abundance populations
The Milky Way tomography with APOGEE: intrinsic density distribution and structure of mono-abundance populations
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APOGEE 的银河系断层扫描：单丰度种群的固有密度分布和结构
DOI：
10.1093/mnras/stac1151
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发表时间：
2022
影响因子：
4.8
通讯作者：
Horta, Danny
中科院分区：
文献类型：
--
作者：
Lian, Jianhui;Zasowski, Gail;Mackereth, Ted;Imig, Julie;Holtzman, Jon A.;Beaton, Rachael L.;Bird, Jonathan C.;Cunha, Katia;Fernández-Trincado, José G.;Horta, Danny
单丰度群体的空间分布(地图，在[Fe/H]和[Mg/Fe]中选择)反映了星系中的化学和结构演化，并对星系形成模型施加了强烈的约束。在本文中，我们利用远地点数据，在仔细考虑观测选择函数后，推导出银河系地图的本征密度分布。我们发现，单一的指数分布并不足以描述银河系的圆盘。单独的地图和完整的圆盘都表现出破缺的径向密度分布；在银河系内部，密度随半径的变化相对恒定，超过破缺半径后密度迅速下降。我们用二维密度模型来拟合作为半径和垂直高度的函数的本征密度分布，该模型同时考虑了破碎的径向轮廓和标尺高度的径向变化(即张开)。在不同的地图之间有大量不同的结构参数，表明银河系强烈的结构演化。一个令人惊讶的结果是，高α地图显示出最强烈的耀斑。年轻的太阳丰度图显示了最短的尺度高度和最小的耀斑，表明最近和正在进行的恒星形成仅限于盘面。最后，我们得到了化学定义的薄盘和厚盘的本征密度分布和相应的结构参数。化学厚盘和薄盘的局部表面质量密度分别为5.62%±0.08和15.69%±0.32nM⊙PC−2，表明这是一个局部表面质量密度比为36% 的巨型厚盘。
The spatial distribution of mono-abundance populations (MAPs, selected in [Fe/H] and [Mg/Fe]) reflect the chemical and structural evolution in a galaxy and impose strong constraints on galaxy formation models. In this paper, we use APOGEE data to derive the intrinsic density distribution of MAPs in the Milky Way, after carefully considering the survey selection function. We find that a single exponential profile is not a sufficient description of the Milky Way’s disc. Both the individual MAPs and the integrated disc exhibit a broken radial density distribution; densities are relatively constant with radius in the inner Galaxy and rapidly decrease beyond the break radius. We fit the intrinsic density distribution as a function of radius and vertical height with a 2D density model that considers both a broken radial profile and radial variation of scale height (i.e. flaring). There is a large variety of structural parameters between different MAPs, indicative of strong structure evolution of the Milky Way. One surprising result is that high-α MAPs show the strongest flaring. The young, solar-abundance MAPs present the shortest scale height and least flaring, suggesting recent and ongoing star formation confined to the disc plane. Finally we derive the intrinsic density distribution and corresponding structural parameters of the chemically defined thin and thick discs. The chemical thick and thin discs have local surface mass densities of 5.62 ± 0.08 and 15.69 ± 0.32 M⊙pc−2, respectively, suggesting a massive thick disc with a local surface mass density ratio between thick to thin disc of 36 per cent.