标题： 精细结构常数在宇宙时间尺度上的值 显示英文标题

标题： The value of the fine structure constant over cosmological times

摘要： 对SDSS DR6中分类为类星体的天体的光学光谱进行分析，目的是确定过去精细结构常数的值，然后检查该常数在宇宙时间尺度上的可能变化。 通过测量类星体星云发射中的[OIII]双线(4959和5008)的精细结构线的位置来进行分析。 从红移z < 0.8的类星体样本中，根据[OIII]线的振幅和宽度选择了一个子样本。 使用了两种不同的方法来确定[OIII]双线的位置，两种方法都给出了相似的结果。 使用包含1568个此类光谱的干净样本，确定了Delta alpha /alpha=(+2.4 +-2.5) x 10^{-5}(在红移范围0-0.8内)。 使用更多数量的光谱使得基于相同方法的先前限制有了约5倍的改进。 总的来说，我们没有发现alpha在这样的宇宙时间尺度上发生变化的证据。 与我们的结果相容的平均变化是1/ <t> Delta alpha/alpha=(+0.7 +- 0.7) x 10^{-14}yr^{-1}。 该分析扩展到了[NeIII]和[SII]双线，尽管由于这些双线在类星体中通常比[OIII]更暗，且其中一些受到系统误差的影响，因此它们的实用性有限。 显示英文摘要

摘要： The optical spectra of objects classified as QSOs in the SDSS DR6 are analyzed with the aim of determining the value of the fine structure constant in the past and then check for possible changes in the constant over cosmological timescales. The analysis is done by measuring the position of the fine structure lines of the [OIII] doublet (4959 and 5008) in QSO nebular emission. From the sample of QSOs at redshifts z < 0.8 a subsample was selected on the basis of the amplitude and width of the [OIII] lines. Two different method were used to determine the position of the lines of the [OIII] doublet, both giving similar results. Using a clean sample containing 1568 of such spectra, a value of Delta alpha /alpha=(+2.4 +-2.5) x 10^{-5} (in the range of redshifts 0-0.8) was determined. The use of a larger number of spectra allows a factor ~5 improvement on previous constraints based on the same method. On the whole, we find no evidence of changes in alpha on such cosmological timescales. The mean variation compatible with our results is 1/ <t> Delta alpha/alpha=(+0.7 +- 0.7) x 10^{-14} yr^{-1}. The analysis was extended to the [NeIII] and [SII] doublets, although their usefulness is limited due to the fact that all these doublets in QSOs tend to be fainter than [OIII], and that some of them are affected by systematics.