Are peculiar velocity surveys competitive as a cosmological probe
Are peculiar velocity surveys competitive as a cosmological probe
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DOI：
10.1093/mnras/stu1610
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发表时间：
2013-12
影响因子：
4.8
通讯作者：
J. Koda;C. Blake;T. Davis;C. Magoulas;C. Springob;Morag I. Scrimgeour;Andrew Johnson;G. Poole-
中科院分区：
文献类型：
--
作者：
J. Koda;C. Blake;T. Davis;C. Magoulas;C. Springob;Morag I. Scrimgeour;Andrew Johnson;G. Poole-
特殊的速度巡天，除了测量红移外，还直接从标准烛光测量星系的速度，可以对低红移结构的增长率提供强有力的约束。这一改进源于星系密度和奇特速度之间的物理关系，它大大减少了宇宙方差。我们使用Fisher矩阵预测表明，对于星系数密度为10（-2）（h（-1）Mpc）（-3）的巡天，如果我们能够使用波数k <= 0.2 h Mpc（-1）的所有信息，那么与单独的密度相比，特殊速度数据可以将增长率约束提高约2倍。在k = 0.2 h Mpc（-1）时缺乏精确的理论模型，与仅红移观测相比的改善甚至更大--当k <= 0.1 h Mpc（-1）时大约是5倍。未来的特殊速度巡天，通过星云多色分析进行的天文成像巡天（TAIPAN），以及全天空H I巡天，宽场ASKAP L波段传统全天空盲视巡天（WALLABY）和韦斯特博克北方天空H I巡天（WNSHS），可以测量到在z接近0.025处的3%的增长率。虽然速度子样本比来自同一调查的红移样本小一个数量级，但与没有速度测量的同一调查相比，它将约束提高了40%。特殊速度巡天还可以测量作为波数函数的增长率，在宽度为Δ k = 0.01 h Mpc（-1）的区间内，k <= 0.1 h Mpc（-1）的不确定性为15%-30%，这比星系密度有很大的改进。这种在非常大尺度上的测量可以通过尺度相关的增长率或星系偏差来检测修改的重力或非高斯性的特征。我们使用N体模拟详细测试我们的建模。
Peculiar velocity surveys, which measure galaxy velocities directly from standard candles in addition to redshifts, can provide strong constraints on the growth rate of structure at low redshift. The improvement originates from the physical relationship between galaxy density and peculiar velocity, which substantially reduces cosmic variance. We use Fisher matrix forecasts to show that peculiar velocity data can improve the growth rate constraints by about a factor of 2 compared to density alone for surveys with galaxy number density of 10(-2) (h(-1) Mpc)(-3), if we can use all the information for wavenumber k <= 0.2 h Mpc(-1). In the absence of accurate theoretical models at k = 0.2 h Mpc(-1), the improvement over redshift-only surveys is even larger - around a factor of 5 for k <= 0.1 h Mpc(-1). Future peculiar velocity surveys, Transforming Astronomical Imaging surveys through Polychromatic Analysis of Nebulae (TAIPAN), and the all-sky H I surveys, Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) and Westerbork Northern Sky H I Survey (WNSHS), can measure the growth rate to 3 per cent at z similar to 0.025. Although the velocity subsample is about an order of magnitude smaller than the redshift sample from the same survey, it improves the constraint by 40 per cent compared to the same survey without velocity measurements. Peculiar velocity surveys can also measure the growth rate as a function of wavenumber with 15-30 per cent uncertainties in bins with widths Delta k = 0.01 h Mpc(-1) in the range k <= 0.1 h Mpc(-1), which is a large improvement over galaxy density only. Such measurements on very large scales can detect signatures of modified gravity or non-Gaussianity through scale-dependent growth rate or galaxy bias. We test our modelling in detail using N-body simulations.