FROM GALAXY CLUSTERS TO ULTRA-FAINT DWARF SPHEROIDALS: A FUNDAMENTAL CURVE CONNECTING DISPERSION-SUPPORTED GALAXIES TO THEIR DARK MATTER HALOS
FROM GALAXY CLUSTERS TO ULTRA-FAINT DWARF SPHEROIDALS: A FUNDAMENTAL CURVE CONNECTING DISPERSION-SUPPORTED GALAXIES TO THEIR DARK MATTER HALOS
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从星系团到超微弱矮球体：连接色散支持星系与其暗物质晕的基本曲线
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发表时间：
2010
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通讯作者：
Joe Wolf
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作者：
E. Tollerud;J. Bullock;G. Graves;Joe Wolf
我们研究的色散支持的星系超过8个数量级的光度的标度关系，通过将标准的基本面参数转换成一个空间的质量，半径和光度。半径变量r1/2是去投影（三维）的半光半径，质量变量M1/2是在这个半径内的总引力质量，L1/2是光度的一半。我们发现，从超微弱的矮球状体到巨大的星系团球状体，色散支持的星系在这个MRL空间中沿着一维的“基本曲线”散射。质量-半径-光度关系从最暗的矮球状星系的M1/2 <$r1.441/2 <$L0.301/2过渡到最亮的星系团球状体的M1/2 <$r1.421/2 <$L3.21/2。暗端的M1/2 − L1/2斜率较弱可能意味着势阱深度限制了小星系的星系形成，而亮端对L1/2的依赖性较强则表明重子物理限制了大质量星系的星系形成。这条曲线的质量-半径投影可以与Λ CDM晕的中位暗物质晕质量分布进行比较，以便为跨越7个Mvir数量级的星系构建维里质量-光度关系（Mvir-L）。独立于任何全球丰度或聚类信息，我们发现（球状）星系的形成需要在Mvir 1012 M的晕中最有效，并且在这个尺度之上和之下变得效率低下。此外，这种用于推导Mvir-L的轮廓匹配技术在高光度和低光度极端（暗物质分数最高）下最准确，因此与依赖于具有良好采样的光度函数的统计方法非常互补。我们还考虑了这种关系的散射的意义和效用，并发现在dSph制度的观测误差几乎是在我们可以探索的亮度维里质量关系的内在散射点。最后，我们注意到，纯粹的恒星系统，如球状星团和超紧凑的矮星不遵循基本的曲线关系。这使得它们可以很容易地与MRL空间中以暗物质为主的dSph星系区分开来。
We examine scaling relations of dispersion-supported galaxies over more than eight orders of magnitude in luminosity by transforming standard fundamental plane parameters into a space of mass, radius, and luminosity. The radius variable r1/2 is the deprojected (three-dimensional) half-light radius, the mass variable M1/2 is the total gravitating mass within this radius, and L1/2 is half the luminosity. We find that from ultra-faint dwarf spheroidals to giant cluster spheroids, dispersion-supported galaxies scatter about a one-dimensional “fundamental curve” through this MRL space. The mass–radius–luminosity relation transitions from M1/2 ∼ r1.441/2 ∼ L0.301/2 for the faintest dwarf spheroidal galaxies to M1/2 ∼ r1.421/2 ∼ L3.21/2 for the most luminous galaxy cluster spheroids. The weakness of the M1/2 − L1/2 slope on the faint end may imply that potential well depth limits galaxy formation in small galaxies, while the stronger dependence on L1/2 on the bright end suggests that baryonic physics limits galaxy formation in massive galaxies. The mass–radius projection of this curve can be compared to median dark matter halo mass profiles of ΛCDM halos in order to construct a virial mass–luminosity relationship (Mvir–L) for galaxies that spans seven orders of magnitude in Mvir. Independent of any global abundance or clustering information, we find that (spheroidal) galaxy formation needs to be most efficient in halos of Mvir ∼ 1012 M☉ and to become inefficient above and below this scale. Moreover, this profile matching technique for deriving the Mvir–L is most accurate at the high- and low-luminosity extremes (where dark matter fractions are highest) and is therefore quite complementary to statistical approaches that rely on having a well-sampled luminosity function. We also consider the significance and utility of the scatter about this relation, and find that in the dSph regime observational errors are almost at the point where we can explore the intrinsic scatter in the luminosity–virial mass relation. Finally, we note that purely stellar systems such as globular clusters and ultra-compact dwarfs do not follow the fundamental curve relation. This allows them to be easily distinguished from dark-matter-dominated dSph galaxies in MRL space.