Comparisons of Infrared Colors and Emission-line Intensities between Two types of Seyfert 2 Galaxies     

Lin-peng  Cheng  Yong-Heng  Zhao 《中国天文和天体物理学报》2002,2(5):408-418

We study the relation between the infrared colors[ OⅢ] emission lines,gaseous absorbing column density(NH) ,and the detectability of the polarized (hidden)broad-line region(HBLR) in a large sample of 75 Seyfert 2 galaxies(Sy2s).From the indicators of star-formation activity,f60/f100 and LFIR/LB,we find some evidence that the Sy2s without HBLR show higher star-formation activities than those with HBLR,in agreement with previous prediction.Also,we confirm that the HBLR Sy2s tend to have a larger luminosity ratio of the core to the host galaxy,suggesting that the HBLR Sy2s display more powerful AGN activity.Howerver,the level of obscuration found in previous papers in nearly indistinguishable between the two types of Sy2s.The results support the statement that the non-HBLR Sy2s,with a weaker core component and a stronger star-formation activity component,are intrinsically different from the HBLR Sy2s,which are Sy1 systems with a hidden powerful AGN core and a low star-formation activity.The indications are that the non-HBLR Sy2s might be at an earlier evolutionary phase than the HBLR Sy2s.  相似文献   

Complex component analysis of shear-wave splitting: theory   总被引：2，自引：0，他引：2  

Xiang-Yang Li  Stuart Crampin 《Geophysical Journal International》1991,107(3):597-604

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Faraday rotation in the VLBI core of BL Lacertae     

C. Reynolds  T.V. Cawthorne  D.C. Gabuzda 《Monthly notices of the Royal Astronomical Society》2001,327(4):1071-1080

External Faraday rotation has been detected in both the core and the parsec-scale jet of BL Lac in a four-frequency very long baseline interferometry (VLBI) experiment. This unexpected result indicates the presence of significant amounts of thermal gas close to the nucleus of this object. The rotation measure (RM) in the jet components is constant, and differs from the currently accepted Galactic RM, indicating that this value (−205 rad m⁻²) is not applicable to the components in the parsec-scale jet. The similarity of the RM in these jet components leads us to suspect that the jet RM is caused by a foreground screen in our Galaxy, although we cannot rule out a combination of Galactic RM and RM local to the jet. If the jet RM is due solely to the Galaxy, this would mean that the currently accepted value of the foreground RM (−205 rad m⁻² ) is not correct, either because the value changed between 1982 and 1997, or because the assumption of no intrinsic source rotation was incorrect, as it was at our later epoch of observation. Our observations suggest a value of     .
After correcting for the foreground RM, the core value is −427 rad m⁻², which is unexpected since, owing to the weakness of their line emission, BL Lac objects are often assumed to be depleted in gas. The core RM appears to be variable, probably because of the presence of at least two polarized components close to the core the relative contributions of which vary with time.  相似文献   

On the formation of cluster radio relics     

T. A.Enßlin  M.Brüggen 《Monthly notices of the Royal Astronomical Society》2002,331(4):1011-1019

In several merging clusters of galaxies so-called cluster radio relics have been observed. These are extended radio sources which do not seem to be associated with any radio galaxies. Two competing physical mechanisms to accelerate the radio-emitting electrons have been proposed: (i) diffusive shock acceleration and (ii) adiabatic compression of fossil radio plasma by merger shock waves. Here the second scenario is investigated. We present detailed three-dimensional magneto-hydrodynamical simulations of the passage of a radio plasma cocoon filled with turbulent magnetic fields through a shock wave. Taking into account synchrotron, inverse Compton and adiabatic energy losses and gains, we evolved the relativistic electron population to produce synthetic polarization radio maps. On contact with the shock wave the radio cocoons are first compressed and finally torn into filamentary structures, as is observed in several cluster radio relics. In the synthetic radio maps the electric polarization vectors are mostly perpendicular to the filamentary radio structures. If the magnetic field inside the cocoon is not too strong, the initially spherical radio cocoon is transformed into a torus after the passage of the shock wave. Very recent, high-resolution radio maps of cluster radio relics seem to exhibit such toroidal geometries in some cases. This supports the hypothesis that cluster radio relics are fossil radio cocoons that have been revived by a shock wave. For a late-stage relic the ratio of its global diameter to the filament diameter should correlate with the shock strength. Finally, we argue that the total radio polarization of a radio relic should be well correlated with the three-dimensional orientation of the shock wave that produced the relic.  相似文献   

Bistable profile illumination in pulsars B0919+06 and B1859+07     

Joanna M. Rankin  Cameron Rodriguez  Geoffrey A. E. Wright 《Monthly notices of the Royal Astronomical Society》2006,370(2):673-680

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Spectropolarimetry of O supergiants     

Tim J. Harries  Ian D. Howarth  Christopher J. Evans 《Monthly notices of the Royal Astronomical Society》2002,337(1):341-355

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2022年1月8日青海门源6.9级地震短临异常跟踪分析     

冯丽丽  李霞  赵玉红  张朋涛 《中国地震》2022,38(1):12-20

2022年1月8日青海门源县发生6.9级地震,此次地震前青海地区出现了大量地球物理观测异常。2021年10月下旬青海地区出现地磁垂直强度极化高值异常,10月27日异常台站最多,并在门源-祁连至兴海地区形成一个面积约为6.6×10⁴km²的高值异常区;此外,2021年7—11月青海地区8项地下流体观测数据出现准同步异常变化。结合青海及周边地区历史震例的分析结果,认为2021年11月23日至2022年1月23日,青海西北部地磁垂直强度极化高值区内可能发生5.6～6.4级地震。门源6.9级地震发生在地磁垂直强度极化异常出现后的73天,震中位于预测区的边缘,地震的发生时间和地点与预测意见一致,但震级超出预测意见上限值0.5级。此次地震前基于地球物理观测地震预测指标体系开展的短临异常跟踪分析过程,对中国大陆西部地震预报工作具有一定的参考意义。  相似文献   

深部地热能开发保温管技术研究现状及发展趋势          下载免费PDF全文

杜垚森  封优生  伍晓龙  师敏  高鹏举  汤小仁  赵远  王晓赛  王庆晓  董向宇  李秀峰 《探矿工程》2022,49(6):138-145

地热能是一种清洁的可再生能源,用地热能替代高碳能源是减少碳排放的有效途径之一。井下保温管技术是影响地热能开采效率的关键技术之一。本文从保温管的结构、材料、保温材料及制作工艺方面介绍了井下保温管的发展研究现状,指出纳米保温材料与真空油管的融合将是未来的发展趋势,真空纳米保温管是用于深部地热能开采的首选,同时也指出了真空纳米保温管的基础结构因素对保温性能的影响机制是研究的重点,为优化保温管的制作工艺、降本增效提供参考。  相似文献   

絮凝−真空−电渗联合加固滩涂软土的模型试验研究     

张雷  吕延栋  王炳辉  金丹丹  竺明星  方晨 《岩土力学》2022,43(9):2383-2390

针对真空预压作用下排水板淤堵与排水条件受限等问题,提出絮凝−真空−电渗联合加固法。首先通过沉降柱试验确定合适的有机絮凝剂,然后采用该絮凝剂,分别在 48 h（开始介入真空预压,固结度为0 ）、60 h（排水速率明显下降,固结度为60%）及 84 h（排水速率近乎 0,固结度为 80%）时介入电渗,开展不同电渗介入时间的絮凝−真空−电渗联合加固试验。试验从排水量、十字板剪切强度、含水率与孔压等对比分析联合加固的有效性,确定其最佳电渗介入时间。试验结果表明：当固结度为 80% 时介入电渗,絮凝−真空−电渗联合加固法能够有效地抑制排水速率减小的趋势,增长有效排水时间。同时,土体的抗剪强度和承载力亦得到大幅提升,孔压消散更加均匀。此外,在阳离子聚丙烯酰胺絮凝剂的作用下,初始排水速率快,在一定程度上使土体的渗透性得到提升,有效地解决了排水板淤堵问题,说明絮凝−真空−电渗联合加固法具有较强的优越性。  相似文献   

ALOS PALSAR全极化图像分类研究     

杨金玲  朱继文  梁欣  张玉娟 《测绘与空间地理信息》2015,(10):1-3

极化干涉相干矩阵服从复Wishart分布,通过对相关系数的分析可以获得不同的地物类别。在总结极化干涉非监督Wishart ML分类流程的基础上,基于该方法对塔河地区全极化PALSAR数据进行了分类,研究结果表明:基于极化干涉的分类方法能够有效区分不同散射机制对应的地物,该分类方法具有较强的适应性,并且类间边界比较明显,这些分类信息为森林资源的开发和利用提供了参考。  相似文献