变化精细结构常数的Keck约束：波长校准误差
Keck constraints on a varying fine-structure constant: wavelength calibration errors
摘要：
凯克望远镜的HIRES摄谱仪先前在143个类星体吸收系统的样本中提供了一个比当前实验室值更小的精细结构常数α的证据：da/a=（-0.57+/-0.11 x10 ^{-5}。这是基于各种金属离子的转变，如果α变化，则会经历不同的相对速度变化。这一结果还没有被其他望远镜和摄谱仪的测量有力地反驳或证实;这样做仍然至关重要。同样重要的是要考虑新的可能的仪器系统的影响，可以解释凯克/HIRES的结果。Griest等人（2009，arXiv：0904.4725v1）最近发现了HIRES中阶梯光栅级波长尺度的畸变，其典型振幅为+/-250 m/s。在这里，我们调查的影响，这种扭曲可能对凯克/HIRES不同的α结果。我们表明，它们会导致一个随机的影响da/a从吸收体到吸收体，因为系统是在不同的红移，将相关的吸收线在不同的位置，在不同的中阶梯顺序。对da/a的影响的典型幅度为每个吸收体约0.4x10^{-5}，与样本中da/a的中值误差（约1.9x10^{-5}）相比，相对较小。因此，如果应用我们计算的校正，则加权平均值的变化小于0.05x10^{-5}。尽管如此，我们敦促谨慎，特别是对旨在实现高精度da/a测量的分析，对个别系统或小样本，更详细地了解这种阶内失真及其对观测参数的依赖性是很重要的，如果他们要避免或可靠地建模。[摘要]
英文摘要：
The Keck telescope's HIRES spectrograph has previously provided evidence for a smaller fine-structure constant, alpha, compared to the current laboratory value, in a sample of 143 quasar absorption systems: da/a=(-0.57+/-0.11)x10^{-5}. This was based on a variety of metal-ion transitions which, if alpha varies, experience different relative velocity shifts. This result is yet to be robustly contradicted, or confirmed, by measurements on other telescopes and spectrographs; it remains crucial to do so. It is also important to consider new possible instrumental systematic effects which may explain the Keck/HIRES results. Griest et al. (2009, arXiv:0904.4725v1) recently identified distortions in the echelle order wavelength scales of HIRES with typical amplitudes +/-250m/s. Here we investigate the effect such distortions may have had on the Keck/HIRES varying alpha results. We demonstrate that they cause a random effect on da/a from absorber to absorber because the systems are at different redshifts, placing the relevant absorption lines at different positions in different echelle orders. The typical magnitude of the effect on da/a is ~0.4x10^{-5} per absorber which, compared to the median error on da/a in the sample, ~1.9x10^{-5}, is relatively small. Consequently, the weighted mean value changes by less than 0.05x10^{-5} if the corrections we calculate are applied. Nevertheless, we urge caution, particularly for analyses aiming to achieve high precision da/a measurements on individual systems or small samples, that a much more detailed understanding of such intra-order distortions and their dependence on observational parameters is important if they are to be avoided or modelled reliably. [Abridged]
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