When is stacking confusing? The impact of confusion on stacking in deep H I galaxy surveys
When is stacking confusing? The impact of confusion on stacking in deep H I galaxy surveys
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DOI：
10.1093/mnras/stv2394
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发表时间：
2015-10
影响因子：
4.8
通讯作者：
Michael G. Jones;M. Haynes;R. Giovanelli;E. Papastergis
中科院分区：
文献类型：
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作者：
Michael G. Jones;M. Haynes;R. Giovanelli;E. Papastergis
我们提出了一个分析模型来预测在一般的HI调查中，混乱源对叠加光谱的HI质量贡献。基于Aregbo Legacy Fast Alfa(Aregbo Legacy Fast Alfa)关联函数，该模型与叠加帕克斯望远镜数据中存在的混淆估计值一致，并被用来预测混乱将如何限制最深平方公里阵列前兆HI调查中的叠加。与Laduma(与Meerkat一起观察遥远的宇宙)和Dingo UDEEP(中性气体起源深度调查-超深)数据的堆叠只会受到轻微的混乱影响，如果他们的目标合成波束大小能够达到10角秒的话。任何明显超过这个值的束流大小都将导致堆叠在混乱的源中包含的质量相当于(或大于)在所有红移情况下通过堆叠可以检测到的质量。CHILES(COSMOS HI大型星系外勘测)5角秒的分辨率足以防止混乱影响其整个带通范围内数据的堆叠。FAST(500米口径球面望远镜)将受到混乱的阻碍，HI调查可能会变得严重混乱，远远超过z=0.1。我们模型中最大的不确定性是宇宙HI密度和HI关联函数的红移演化。然而，我们认为我们采用的两种理想化情况应该包括真实的演化，并且无论模型选择如何，定性的结论都是不变的。由于混淆(在没有任何检测的情况下)导致的信号的轮廓形状也被建模，揭示了它可以采取具有窄和宽分量的双高斯的形式。
We present an analytic model to predict the HI mass contributed by confused sources to a stacked spectrum in a generic HI survey. Based on the ALFALFA (Arecibo Legacy Fast ALFA) correlation function, this model is in agreement with the estimates of confusion present in stacked Parkes telescope data, and was used to predict how confusion will limit stacking in the deepest Square Kilometre Array precursor HI surveys. Stacking with LADUMA (Looking At the Distant Universe with MeerKAT) and DINGO UDEEP (Deep Investigation of Neutral Gas Origins - Ultra Deep) data will only be mildly impacted by confusion if their target synthesized beam size of 10 arcsec can be achieved. Any beam size significantly above this will result in stacks that contain a mass in confused sources that is comparable to (or greater than) that which is detectable via stacking, at all redshifts. CHILES (COSMOS HI Large Extragalactic Survey) 5 arcsec resolution is more than adequate to prevent confusion influencing stacking of its data, throughout its bandpass range. FAST (Five hundred metre Aperture Spherical Telescope) will be the most impeded by confusion, with HI surveys likely becoming heavily confused much beyond z = 0.1. The largest uncertainties in our model are the redshift evolution of the HI density of the Universe and the HI correlation function. However, we argue that the two idealized cases we adopt should bracket the true evolution, and the qualitative conclusions are unchanged regardless of the model choice. The profile shape of the signal due to confusion (in the absence of any detection) was also modelled, revealing that it can take the form of a double Gaussian with a narrow and wide component.