A Subset of Quasars Identified by Large Values of Their Doppler Redshift
A Subset of Quasars Identified by Large Values of Their Doppler Redshift
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DOI：
10.1086/521324
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发表时间：
2007-11
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影响因子：
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通讯作者：
Lu Lu-Lu;Yi-Ping Qin;Alok C Gupta
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文献类型：
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作者：
Lu Lu-Lu;Yi-Ping Qin;Alok C Gupta
我们从类星体观测到的发射红移和吸收红移计算了类星体样本的多普勒红移。我们只选择那些吸收红移大于相应的发射红移（即zabs > zem）的红移。该样本是从包含784个类星体光谱的类星体目录中提取的，其中检测到11,298个吸收系统和20,837条吸收线。我们从123个类星体中获得了256个具有zabs > zem的吸收系统。我们发现，在多普勒红移的分布中存在双峰结构，一个峰位于zDopp≃0.00处，另一个峰位于zDopp≃0.01处。在第二峰zDopp处，我们发现一类类星体的多普勒红移大于0.0088。我们的分析表明，这类类星体通常比那些多普勒红移小于0.0088的类星体更亮。这些类星体吸收体的多普勒速度集中在~3000 km s-1左右。这种速度很可能是由于物质落向类星体的中心区域而产生的。
We have calculated the Doppler redshifts for a sample of quasars from their observed emission and absorption redshifts. We selected only those absorption redshifts that are larger than the corresponding emission redshifts (i.e., zabs > zem). The sample was extracted from a quasar catalog that contains spectra of 784 quasars, for which 11,298 absorption systems and 20,837 absorption lines were detected. We obtained 256 absorption systems with zabs > zem from 123 quasars. We find that there is a bimodal structure in the distribution of the Doppler redshifts, with one peak being located at zDopp ≃ 0.00 and the other at zDopp ≃ 0.01. Around the second peak, zDopp ≃ 0.01, we identify a subset of quasars with Doppler redshifts greater than 0.0088. Our analysis shows that quasars in this subset are generally brighter than those with Doppler redshifts less than 0.0088. The Doppler velocities of the absorbers of these quasars are concentrated around ~3000 km s-1. This velocity likely arises from material falling toward the central region of the quasars that originates beyond the torus.