在大尺度射电巡天中探测宇宙偶极子各向异性
Detecting the Cosmic Dipole Anisotropy in Large-Scale Radio Surveys
摘要：
在大规模射电观测中，对源的天空分布中的偶极子各向异性的探测可以用来约束我们相对于各向同性分布的河外射电源群的局部运动的幅度和方向。这样的人口被预测存在于各向同性膨胀的宇宙中的宇宙学红移。观测到河外射电源群的中位红移为z ~ 1，比宇宙微波背景（z ~ 1100）晚得多。我认为在无线电调查中的速度偶极子各向异性的可探测性具有有限数量的源计数。文中还详细讨论了从射电源计数中检测速度偶极子的统计意义。我发现，现有的大规模无线电测量目录没有足够数量的源来检测具有统计意义的预期速度偶极子，即使可以完全消除测量掩蔽和通量校准复杂性（即，如果测量和观测仪器都是完美的）。然而，偶极各向异性应该很容易检测到未来的无线电调查计划与下一代无线电设施，如低频阵列和平方公里阵列;严格的偶极子幅度和方向的限制应该是可能的，如果通量校准问题可以充分减少或纠正和当地来源的污染消除。
英文摘要：
The detection of a dipole anisotropy in the sky distribution of sources in large-scale radio surveys can be used to constrain the magnitude and direction of our local motion with respect to an isotropically distributed extragalactic radio source population. Such a population is predicted to be present at cosmological redshifts in an isotropically expanding universe. The extragalactic radio source population is observed to have a median redshift of z ~ 1, a much later epoch than the cosmic microwave background (z ~ 1100). I consider the detectability of a velocity dipole anisotropy in radio surveys having a finite number of source counts. The statistical significance of a velocity dipole detection from radio source counts is also discussed in detail. I find that existing large-scale radio survey catalogs do not have a sufficient number of sources to detect the expected velocity dipole with statistical significance, even if survey masking and flux calibration complications can be completely eliminated (i.e., if both the surveys and observing instruments are perfect). However, a dipole anisotropy should be easily detectable in future radio surveys planned with next-generation radio facilities, such as the Low Frequency Array and the Square Kilometer Array; tight constraints on the dipole magnitude and direction should be possible if flux calibration problems can be sufficiently minimized or corrected and contamination from local sources eliminated.
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