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Optimizing the tip of the red giant branch distance estimator

机译：优化红色巨型分支距离估计器的尖端

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Until very recently, our knowledge of the local peculiar velocity field has been severely hampered by the lack of reliable distance measurements. HST has dramatically changed this situation, allowing astronomers to obtain accurate distances to more than 150 nearby galaxies. This number could easily reach 400 if enough observing time would be dedicated to snapshot observation of the objects in the catalog of Karachentsev et al. (2004). Such a dense grid of objects correctly placed in their 3D position would provide key information on the amplitude of peculiar motions, the radial domain of bound groups, the clustering and morphological segregation properties of galaxies, and the incidence of extreme dwarfs galaxies. The key instrument to measure distances with HST is the Tip of the Red Giant Branch technique. The full exploitation of this powerful distance estimator requires a deeper understanding of the possible sources of errors and biases, such as the absolute calibration of the I-band magnitude of the tip and its dependency on age and metallicity of the underlying population, the possible contamination by AGB stars, the breakdown of the methodology in sparsely populated colour-magnitude diagrams and when the tip is close to the photometric limit.
机译：直到最近，我们对局部特殊速度场的了解受到可靠距离测量的严重阻碍。 HST大大改变了这种情况，使天文学家能够在150多个附近的星系上获得准确的距离。如果足够的观察时间将致力于快照观察Karachentsev等人的目录中的对象的快照观察，此数字可以很容易地达到400。 （2004）。正确地放置在其3D位置的物体的这种致密电网将提供有关奇迹运动的幅度，结合基团的径向结构域，星系的聚类和形态分离特性的关键信息，以及极端矮星的发生率。用HST测量距离的关键仪器是红色巨型分支技术的尖端。这种强大的距离估计器的完全开发需要更深入地了解可能的误差和偏差源，例如尖端的I波段的绝对校准及其对底层群体的年龄和金属性的依赖性，可能的污染通过AGB Stars，稀疏填充的颜色幅度图中的方法的细分以及尖端靠近光度限制。

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