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首页> 外文期刊>The Astrophysical Journal. Supplement Series >THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: AN INVESTIGATION OF BIASES IN C IV EMISSION LINE PROPERTIES
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THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: AN INVESTIGATION OF BIASES IN C IV EMISSION LINE PROPERTIES

机译：Sloan Digital Sky Survey Reaceratoration Mapping项目：C IV排放线属性中的偏差调查

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摘要

We investigate the dependence on data quality of quasar properties measured from the C IV emission line region at high redshifts. Our measurements come from 32 epochs of Sloan Digital Sky Survey Reverberation Mapping Project spectroscopic observations of 482 z > 1.46 quasars. We compare the differences between measurements made from the single-epoch (SE) and coadded spectra, focusing on the C IV lambda 1549 emission line because of its importance for studies of high-redshift quasar demographics and physical properties, including black hole masses. In addition to statistical errors increasing (by factors of similar to 2-4), we find increasing systematic offsets with decreasing signal-to-noise ratio (S/N). The systematic difference (measurement uncertainty) in our lowest-S/N (<5) subsample between the SE and coadded spectrum (i) C IV equivalent width is 17 angstrom (31 angstrom), (ii) centroid wavelength is < 1 angstrom (2 angstrom), and fractional velocity widths, Delta V/V, characterized by (iii) the line dispersion, sigma(l), is 0.104 (0.12), and (iv) the mean absolute deviation (MAD) is 0.072 (0.11). These remain smaller than the 1 sigma measurement uncertainties for all subsamples considered. The MAD is found to be the most robust line-width characterization. Offsets in the C IV FWHM velocity width and the C IV profile characterized by FWHM/sigma(l) are only smaller than the statistical uncertainties when S/N > 10, although offsets in lower-S/N spectra exceed the statistical uncertainties by only a factor of similar to 1.5 and may depend on the type of functional fit to the line. Characterizing the C IV line profile by the kurtosis is the least robust property investigated, as the median systematic coadded-SE measurement differences are larger than the statistical uncertainties for all S/N subsamples.
机译：我们研究了在高射频处的C IV发射线区域测量的Quasar属性的数据质量的依赖性。我们的测量来自32个Sloan数字天空调查混响映射映射项目光谱观察的482 Z> 1.46 Quasars。我们比较由单时期（SE）和加入的光谱所做的测量之间的差异，专注于C IV Lambda 1549排放线，因为重要的是对高射频准人口统计和物理性质的研究，包括黑洞群众。除了统计误差增加（按照2-4的因素），我们发现越来越大的系统偏移，减少信噪比（S / N）。 SE和加入频谱（I）C IV等效宽度之间的最低S / N（<5）子样本中的系统差异（测量不确定性）是17埃（31埃），（ii）质心波长<1埃（ 2埃）和分数速度宽度，表征（iii）线分散，Sigma（L）的ΔV/ v为0.104（0.12），（iv）平均绝对偏差（MAD）为0.072（0.11） 。这些仍然小于所考虑的所有子样本的1个Σ度不确定性。疯狂被发现是最强大的线宽表征。 C IV FWHM速度宽度和由FWHM / SIGMA（L）特征的C IV曲线仅小于S / N> 10时的统计不确定性，尽管下S / N光谱中的偏移仅超过统计不确定性一个类似于1.5的因素，可以取决于功能适合线的类型。表征C IV线概况通过峰氏症是所研究的最不稳健的财产，因为中值系统的加入-SE测量差异大于所有S / N个归档的统计不确定性。

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