Satellites and haloes of dwarf galaxies
Satellites and haloes of dwarf galaxies
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矮星系的卫星和晕
DOI：
10.1093/mnras/sts054
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发表时间：
2012
影响因子：
4.8
通讯作者：
J. Navarro
中科院分区：
文献类型：
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作者：
L. Sales;Wenting Wang;S. White;J. Navarro
我们使用斯隆数字巡天/数据发布7 （SDSS/DR7）光谱目录研究卫星星系的丰度作为主恒星质量的函数。与以往的研究主要集中在明亮的原星系不同，我们的中心星系的恒星质量范围很广，10(7.5)<= M-*(pri)/M-圆点<= 10(11)，从矮星到中心星团星系。我们的分析证实，当用卫星与主恒星的质量比(m(*)（sat)/ m -*(pri)）表示时，围绕明亮主星的卫星的平均数量是m -*(pri)的一个强函数。另一方面，对于矮原星(M-*（pri) < 10(10) M圆点），卫星丰度在很大程度上与原星质量无关。这些结果与Lambda冷暗物质（Lambda CDM）场景中的星系形成模型一致。我们发现SDSS数据与由Millennium-II模拟构建的半解析模拟星系目录之间有很好的一致性。卫星星系在Lambda CDM中追踪暗物质子结构，因此卫星丰度反映了子结构和星系恒星质量（M-*）对光晕质量M-200的依赖。由于暗物质的子结构几乎是尺度无关的，卫星丰度对原始质量的依赖完全来自于星系质量-晕质量关系中定义明确的特征质量。在矮星系尺度上，模型预测幂律缩放，M-*与M-200（2.5）成正比，相似性被保留，卫星丰度与原始质量无关。对于比M-*-M-200关系的特征质量更亮的原星，卫星丰度随原星质量的增加而增加。我们的研究结果为λ CDM星系形成模型中矮星系质量对晕质量的近似幂律依赖提供了强有力的支持。
We study the abundance of satellite galaxies as a function of primary stellar mass using the Sloan Digital Sky Survey/Data Release 7 (SDSS/DR7) spectroscopic catalogue. In contrast with previous studies, which focused mainly on bright primaries, our central galaxies span a wide range of stellar mass, 10(7.5) <= M-*(pri)/M-circle dot <= 10(11), from dwarfs to central cluster galaxies. Our analysis confirms that the average number of satellites around bright primaries, when expressed in terms of satellite-to-primary stellar mass ratio (m(*)(sat)/M-*(pri)), is a strong function of M-*(pri). On the other hand, satellite abundance is largely independent of primary mass for dwarf primaries (M-*(pri) < 10(10) M-circle dot). These results are consistent with galaxy formation models in the Lambda cold dark matter (Lambda CDM) scenario. We find excellent agreement between SDSS data and semianalytic mock galaxy catalogues constructed from the Millennium-II Simulation. Satellite galaxies trace dark matter substructure in Lambda CDM, so satellite abundance reflects the dependence on halo mass, M-200, of both substructure and galaxy stellar mass (M-*). Since dark matter substructure is almost scale free, the dependence of satellite abundance on primary mass results solely from the well-defined characteristic mass in the galaxy mass-halo mass relation. On dwarf galaxy scales, where models predict a power-law scaling, M-* proportional to M-200(2.5), similarity is preserved and satellite abundance is independent of primary mass. For primaries brighter than the characteristic mass of the M-*-M-200 relation, satellite abundance increases strongly with primary mass. Our results provide strong support for the steep, approximately power-law dependence of dwarf galaxy mass on halo mass envisioned in Lambda CDM galaxy formation models.