A z = 3 Lyα BLOB ASSOCIATED WITH A DAMPED Lyα SYSTEM PROXIMATE TO ITS BACKGROUND QUASAR
A z = 3 Lyα BLOB ASSOCIATED WITH A DAMPED Lyα SYSTEM PROXIMATE TO ITS BACKGROUND QUASAR
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DOI：
10.1088/0004-637x/693/2/l49
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发表时间：
2008-07
期刊：
影响因子：
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通讯作者：
J. Hennawi;J. Prochaska;J. Kollmeier;Zheng Zheng-Zheng
中科院分区：
文献类型：
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作者：
J. Hennawi;J. Prochaska;J. Kollmeier;Zheng Zheng-Zheng
我们报道了一个与z = 3的类星体SDSS J124020.91+145535.6有关的明亮Lyα斑点的发现，这也与来自前景星系的强阻尼Lyα吸收（所谓的近阻尼Lyα（PDLA）系统）相一致。Sloan数字巡天（SDSS）获得的一维光谱显示，在PDLA的波谷上叠加了一条宽的Lyα发射线，其半高宽为500 km s-1，亮度为LLyα = 3.9 × 1043 erg s-1。使用Keck/LRIS光谱仪进行的后续观测证实，该源有一个空间范围超过5″的Lyα星云，对应于大于39 kpc的适当大小。在这个星云中，Lyα的光度很大，其动力机制也被讨论。我们利用MonteCarlo辐射传输模拟研究了kpc尺度PDLA星系的线辐射是由类星体电离通量提供能量的荧光复合辐射的可能性，但发现预测的Lyα通量比观测到的低几个数量级。我们的结论是，Lyα发射与PDLA星系无关，而是类星体宿主固有的，类似于许多活动星系核周围检测到的扩展Lyα“模糊”。PDLA是天然的日冕仪，它在Lyα处阻挡了它们的背景类星体，我们讨论了如何使用类似于SDSS J124020.91+145535.6的系统来成像PDLA星系中的中性氢的剪影，背景类星体的扩展Lyα发射的屏幕。
We report on the discovery of a bright Lyα blob associated with the z = 3 quasar SDSS J124020.91+145535.6 which is also coincident with strong damped Lyα absorption from a foreground galaxy (a so-called proximate damped Lyα (PDLA) system). The one-dimensional spectrum acquired by the Sloan Digital Sky Survey (SDSS) shows a broad Lyα emission line with a FWHM ≃500 km s-1 and a luminosity of LLyα = 3.9 × 1043 erg s-1 superposed on the trough of the PDLA. Follow-up observations using the Keck/LRIS spectrometer confirm that this source has a Lyα nebula with spatial extent exceeding 5″, corresponding to a proper size >39 kpc. Mechanisms for powering the large Lyα luminosity in this nebula are discussed. We use a Monte Carlo radiative transfer simulation to investigate the possibility that the line emission is fluorescent recombination radiation from a kpc-scale PDLA galaxy powered by the ionizing flux of the quasar, but find that the predicted Lyα flux is several orders of magnitude lower than observed. We conclude that the Lyα emission is not associated with the PDLA galaxy at all, but instead is intrinsic to the quasar's host and similar to the extended Lyα “fuzz” which is detected around many active galactic nuclei. PDLAs are natural coronagraphs that block their background quasar at Lyα and we discuss how systems similar to SDSS J124020.91+145535.6 might be used to image the neutral hydrogen in the PDLA galaxy in silhouette against the screen of extended Lyα emission from the background quasar.