Extragalactic Imprints in Galactic Dust Maps
Extragalactic Imprints in Galactic Dust Maps
复制标题
银河尘埃图中的河外印记
DOI：
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发表时间：
2018
影响因子：
4.9
通讯作者：
B. M'enard
中科院分区：
文献类型：
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作者：
Y. Chiang;B. M'enard
河外天文学依赖于对源测光的精确估计，该测光已对银河系尘埃消光进行了校正。这激发了许多“银河系”尘埃图的创作。我们调查这些地图是否被污染的河外信号使用集群红移技术，即，通过测量一组与光谱物体的角度互相关作为红移的函数。我们的层析分析揭示了银河系外大尺度结构模式的印记，在10个银河系尘埃地图中有9个，包括所有基于红外线的地图以及“恒星”变红的地图。当这样的地图被用于消光校正时，这种河外污染会在毫米级的光度估计中引入红移和尺度依赖的偏差。它可以影响基于对象的分析，如估计哈勃图与超新星，以及空间统计。当测量具有低振幅的角相关函数时，例如透镜诱导的相关性或分布在宽红移范围内的源的角相关性，偏差可以是明显的。正如预期的那样，我们没有检测到任何河外污染的尘埃图推断21厘米高的观测。这种地图提供了广泛使用的红外地图的替代方法，但依赖于恒定的灰尘与气体比率的假设。我们注意到，使用宽视场红外巡天探测器12 μm地图敏感的多环芳烃（PAH），间接尘埃示踪剂，我们检测到弥漫的河外PAH的背景到z = 2。最后，我们提供了一个程序，以尽量减少有偏见的震级校正与河外印记的地图的水平。
Extragalactic astronomy relies on the accurate estimation of source photometry corrected for Milky Way dust extinction. This has motivated the creation of a number of “Galactic” dust maps. We investigate whether these maps are contaminated by extragalactic signals using the clustering-redshift technique, i.e., by measuring a set of angular cross-correlations with spectroscopic objects as a function of redshift. Our tomographic analysis reveals imprints of extragalactic large-scale structure patterns in nine out of 10 Galactic dust maps, including all infrared-based maps as well as “stellar” reddening maps. When such maps are used for extinction corrections, this extragalactic contamination introduces redshift- and scale-dependent biases in photometric estimates at the millimagnitude level. It can affect both object-based analyses, such as the estimation of the Hubble diagram with supernovae, as well as spatial statistics. The bias can be appreciable when measuring angular correlation functions with low amplitudes, such as lensing-induced correlations or angular correlations for sources distributed over a broad redshift range. As expected, we do not detect any extragalactic contamination for the dust map inferred from 21 cm H i observations. Such a map provides an alternative to widely used infrared-based maps but relies on the assumption of a constant dust-to-gas ratio. We note that, using the Wide-field Infrared Survey Explorer 12 μm map sensitive to polycyclic aromatic hydrocarbons (PAHs), an indirect dust tracer, we detect the diffuse extragalactic PAH background up to z ∼ 2. Finally, we provide a procedure to minimize the level of biased magnitude corrections in maps with extragalactic imprints.
影响因子：
6.5
作者：
Ben Bekhti, N.;Floer, L.;Staveley-Smith, L.
通讯作者：
Staveley-Smith, L.