ON THE RADIO AND OPTICAL LUMINOSITY EVOLUTION OF QUASARS
ON THE RADIO AND OPTICAL LUMINOSITY EVOLUTION OF QUASARS
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DOI：
10.1088/0004-637x/743/2/104
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
J. Singal;V. Petrosian;V. Petrosian;A. Lawrence;Ł. Stawarz;Ł. Stawarz
中科院分区：
文献类型：
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作者：
J. Singal;V. Petrosian;V. Petrosian;A. Lawrence;Ł. Stawarz;Ł. Stawarz
我们同时计算了类星体的射电和光学光度演化，以及定义为射电和光学光度比的射电响度分布R，使用一个流量受限的数据集，该数据集包含636个具有射电和光学通量的类星体。我们首先注意到，在处理多变量数据时，在获得变量的个体分布之前，必须首先确定变量之间的真实相关性，而不是由观测选择效应引入的变量之间的相关性。我们使用Efron和Petrosian开发的方法，这些方法旨在从由于观测偏差而截断的数据集获得无偏相关性、分布和红移演化。发现类星体的数量在射电光度和光学光度之间表现出很强的正相关关系。考虑到这种关联，无论是本征的还是观测诱导的，我们发现在两个波段都有很强的光度演化和红移，其中射电比光学演化要高得多。我们的结论是，通过将光源随机分为射电响亮(R>；10)和射电安静(R<；10)两个群体而获得的光度演化引入了显著的偏差，从而极大地扭曲了结果。我们还构造了局域射电光度函数、光学光度函数和密度演化函数。最后，我们考虑了通过仔细处理选择效应和光度演化而得到的射电响度参数R的分布，以及没有考虑这些因素的原始数据所得到的分布。我们发现这两种分布之间有显著差异，在所考虑的R值范围内的真实分布中没有明显的双峰迹象。因此，我们的结果表明，有些令人惊讶的是，在非常安静的射电类星体和非常响亮的类星体之间，在产生圆盘流出/喷流的效率上并没有关键的切换，而是一种平稳的过渡。此外，在所考虑的样品中，高红移和更亮的光源的效率似乎更高。
We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux-limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multi-variate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that the population of quasars exhibits strong positive correlation between the radio and optical luminosities. With this correlation, whether intrinsic or observationally induced accounted for, we find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio-loud (R > 10) and radio-quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio-loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution for the range of R values considered. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio-quiet and very radio-loud quasars, but rather a smooth transition. Also, this efficiency seems higher for the high-redshift and more luminous sources in the sample considered.