H i intensity mapping: a single dish approach
H i intensity mapping: a single dish approach
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DOI：
10.1093/mnras/stt1082
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发表时间：
2012-09
影响因子：
4.8
通讯作者：
R. Battye;I. Browne;C. Dickinson;G. Heron;B. Maffei;A. Pourtsidou;A. Pourtsidou
中科院分区：
文献类型：
--
作者：
R. Battye;I. Browne;C. Dickinson;G. Heron;B. Maffei;A. Pourtsidou;A. Pourtsidou
我们讨论了用单碟法探测大尺度的H I强度涨落，最终目的是测量重子声振荡(BAO)并限制暗能量的性质。为了表征信号，我们给出了单个红移切片的三维功率谱、二维角功率谱，以及利用基于千禧年模拟的S 3模拟HI星表计算的单个视线谱。我们考虑了在固定灵敏度的低红移和高红移条件下单盘观测的最优仪器设计和测量策略。对于一台T-sys=50K、50个馈源喇叭和1年观测的仪器，我们发现在低红移(z？0.3)下，？40角分的分辨率和？5000°2的测量是接近最佳的，而在较高的红移(z？0.9)时，？10角分和？500°2的分辨率是必要的--这是用一个碟子很难廉价地实现的。来自银河系和河外射电源的连续前景辐射是一个潜在的问题。特别是，我们认为，占主导地位的河外前景可能来自于非常弱的源的聚集。我们评估了它的幅度，并讨论了可能缓解它的方法。然后，我们介绍了我们设计的专用单碟式望远镜的概念，该望远镜旨在探测低红移的BaO。它包括一个照明不足的40米静态碟形天线和一个60单元的接收器阵列，该阵列保持在照明不足的碟形天线上方90米处。为了稳定和控制系统，将使用相关接收器，将每个主要科学波束与指向其中一个天极的天线相对照。我们对我们建议的系统进行了灵敏度评估，并在一年的观测后对功率谱上的不确定性进行了预测。我们发现，以2.4%的精度测量z？0.3的声学标度是可能的，而w可以测量到16%的精度。
We discuss the detection of large-scale H I intensity fluctuations using a single dish approach with the ultimate objective of measuring the baryonic acoustic oscillations (BAO) and constraining the properties of dark energy. To characterize the signal we present 3D power spectra, 2D angular power spectra for individual redshift slices and also individual line-of-sight spectra computed using the S 3 simulated H I catalogue which is based on the Millennium Simulation. We consider optimal instrument design and survey strategies for a single dish observation at low and high redshift for a fixed sensitivity. For a survey corresponding to an instrument with T sys = 50 K, 50 feedhorns and 1 year of observations, we find that at low redshift (z ? 0.3), a resolution of ?40 arcmin and a survey of ?5000 deg 2 is close to optimal, whereas at higher redshift (z ? 0.9) a resolution of ?10 arcmin and ?500 deg 2 would be necessary - something which would be difficult to achieve cheaply using a single dish. Continuum foreground emission from the Galaxy and extragalactic radio sources are potentially a problem. In particular, we suggest that it could be that the dominant extragalactic foreground comes from the clustering of very weak sources. We assess its amplitude and discuss ways by which it might be mitigated. We then introduce our concept for a dedicated single dish telescope designed to detect BAO at low redshifts. It involves an underillumintated static ?40 m dish and a ?60 element receiver array held ?90 m above the underilluminated dish. Correlation receivers will be used with each main science beam referenced against an antenna pointing at one of the celestial poles for stability and control of systematics. We make sensitivity estimates for our proposed system and projections for the uncertainties on the power spectrum after 1 year of observations. We find that it is possible to measure the acoustic scale at z ? 0.3 with an accuracy ?2.4 per cent and that w can be measured to an accuracy of 16 per cent.