亚毫米星系的模拟观测：单碟分辨率和场方差的影响
Simulated observations of sub-millimetre galaxies: the impact of single-dish resolution and field variance
摘要：
最近的观测证据表明，粗糙的角分辨率（$\sim20"$ FWHM）的单碟望远镜在亚毫米波长有偏见的观测星系数量计数混合在一起的亚毫米发射从多个亚毫米星系（SMG）。我们使用光锥计算从更新的实施的\galform半解析模型生成$50$模拟亚毫米调查$0.5$度$^2$在$850$ $μ$ m，考虑到有限的单碟光束的影响，在一个更准确的方式比以前做的。我们发现，混合的SMG确实会导致在明亮的通量（$S_{\mathrm{850}μ\mathrm{m}}\gtrsim1$ mJy）的源提取的计数的增强。通常情况下，$\sim3{-}6$星系的贡献$90\%$的流量的$S_{850μ\mathrm{m}}=5$ mJy源和这些混合星系的物理无关。我们发现，场到场的变化是我们的$S_{850μ\mathrm{m}}>5$ mJy SMG人口，其中有一个中位数红移$z_{50}=2.0$泊松波动，但大于泊松的$S_{850μ\mathrm{m}}>1$ mJy人口（$z_{50}=2.8$）。在与最近针对单盘检测源的干涉测量进行详细比较时，我们重现了单盘和干涉仪数量计数之间的差异，并发现中值红移（$z_{50}=2.5$）与观测值（$z_{50}=2.5\pm 0.2$）非常一致。我们还提出了在$450$和$1100$ $μ$ m，这表明与观测数据吻合良好的单盘调查数计数的预测。
英文摘要：
Recent observational evidence suggests that the coarse angular resolution ($\sim20"$ FWHM) of single-dish telescopes at sub-mm wavelengths has biased the observed galaxy number counts by blending together the sub-mm emission from multiple sub-mm galaxies (SMGs). We use lightcones computed from an updated implementation of the \galform semi-analytic model to generate $50$ mock sub-mm surveys of $0.5$ deg$^2$ at $850$ $μ$m, taking into account the effects of the finite single-dish beam in a more accurate way than has been done previously. We find that blending of SMGs does lead to an enhancement of source extracted number counts at bright fluxes ($S_{\mathrm{850}μ\mathrm{m}}\gtrsim1$ mJy). Typically, $\sim3{-}6$ galaxies contribute $90\%$ of the flux of an $S_{850μ\mathrm{m}}=5$ mJy source and these blended galaxies are physically unassociated. We find that field-to-field variations are comparable to Poisson fluctuations for our $S_{850μ\mathrm{m}}>5$ mJy SMG population, which has a median redshift $z_{50}=2.0$, but are greater than Poisson for the $S_{850μ\mathrm{m}}>1$ mJy population ($z_{50}=2.8$). In a detailed comparison to a recent interferometric survey targeted at single-dish detected sources, we reproduce the difference between single-dish and interferometer number counts and find a median redshift ($z_{50}=2.5$) in excellent agreement with the observed value ($z_{50}=2.5\pm 0.2$). We also present predictions for single-dish survey number counts at $450$ and $1100$ $μ$m, which show good agreement with observational data.
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