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arXiv 1408.4458astro-ph.GAastro-ph.CO
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尘埃、星云辐射和Mg II吸收线系统对QSO射电性质的依赖

The dust, nebular emission and dependence on QSO radio properties of the associated Mg II absorption line systems

Pushpa Khare, Daniel Vanden Berk, Hadi Rahmani, Donald G. York

摘要:

我们研究了1730 Mg II相关吸收系统(AAS;相对于类星体的相对速度,< 3000 km/s;以光速为单位,\b{eta},< 0.01)中的尘埃红化和[O II]发射,其中0.4 < z_abs < 2在SDSS DR 7中,重点关注它们对射电和其他类星体性质的依赖性。我们使用了控制样本,其中几个具有匹配的无线电特性,以表明:(i)在无线电探测(RD)类星体中的AAS引起的尘埃消光比无线电未探测(RUD)类星体中的尘埃消光高2.6 +/- 0.2倍,反过来,在干预系统中引起的尘埃消光高2.9 +/- 0.7倍;在以核心为主的类星体中,AAS造成的尘埃消光比以叶瓣为主的类星体高2.0 +/-0.1倍;(iii)在RD类星体中发生AAS的可能性是RUD类星体的2.1 +/- 0.2倍,在RD类星体中发生AAS的可能性是RUD类星体的1.8 +/- 0.2倍。在质量大于1.23 x 10^{9} M_sun的黑洞类星体中,这种可能性是质量较低的黑洞类星体的0.1倍;(iv)与对照样品相比,原子吸收样品的合成光谱中[O Ⅱ]λ3727发射存在过量通量,其位置在发射红移处。AAS的存在增强了活动星系核和/或宿主星系的O II发射。这种过量对于RD和RUD样品两者是相似的,并且与核心主导的样品相比,在叶主导的样品中是2.5 +/-0.4倍。多余的部分取决于黑洞质量和埃丁顿比。所有这些都指向AAS的内在本质,除了z_abs > z_em的系统可能是坠落星系。

英文摘要:

We studied dust reddening and [O II] emission in 1730 Mg II associated absorption systems (AAS; relative velocity with respect to QSOs, < 3000 km/s; in units of velocity of light, \b{eta}, < 0.01) with 0.4 < z_abs < 2 in the SDSS DR7, focusing on their dependence on the radio and other QSO properties. We used control samples, several with matching radio properties to show (i) AAS in radio detected (RD) QSOs cause 2.6 +/- 0.2 times higher dust extinction than those in radio undetected (RUD) ones which, in turn, cause 2.9 +/- 0.7 times the dust extinction in the intervening systems; (ii) AAS in core-dominated QSOs cause 2.0 +/- 0.1 times higher dust extinction than in lobe-dominated QSOs; (iii) occurrence of AAS is 2.1 +/- 0.2 times more likely in RD QSOs than in RUD QSOs and 1.8 +/- 0.1 time more likely in QSOs having black holes with masses larger than 1.23 x 10^{9} M_sun than in those with lower mass black holes; (iv) there is excess flux in [O II]λ3727 emission in the composite spectra of the AAS samples compared to those of the control samples, which is at the emission redshift. Presence of AAS enhances the O II emission from the AGN and/or the host galaxy. This excess is similar for both RD and RUD samples, and is 2.5 +/- 0.4 times higher in lobe-dominated compared to core-dominated samples. The excess depends on the black hole mass and Eddington ratio. All these point to the intrinsic nature of the AAS except for the systems with z_abs > z_em which could be infalling galaxies.

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