X-ray absorption in distant type II QSOs ,
X-ray absorption in distant type II QSOs ,
复制标题
远处 II 型 QSO 中的 X 射线吸收，
DOI：
10.1051/0004-6361:20079012
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发表时间：
2008
影响因子：
6.5
通讯作者：
U. Leicester
中科院分区：
文献类型：
--
作者：
M. Krumpe;G. Lamer;A. Corral;A. Schwope;F. Carrera;X. Barcons;M. Page;S. Mateos;J. Tedds;M. G. W. A. I. Potsdam;Potsdam;H Germany;Instituto de Fisica de Cantabria Santander;Spain.;Mullard Space Science Laboratory;Holmbury Dorking;United Kingdom.;D. PhysicsAstronomy;U. Leicester
目标。我们给出了一个XMM-牛顿选择的II型类星体样品的X射线光谱分析结果，该样品的z≥ 0.5，0.510 keV通量为0.3− 33× 10 −14 erg/s/cm 2。本文研究了第二类类星体吸收柱密度的分布，并研究了吸收柱密度与X射线光度和红移的关系。方法.我们检查了51个光谱分类的II型类星体可以从XMM-牛顿马拉诺实地调查，XMM-牛顿-2dF广角调查（XWAS），和轴调查，以建立一个明确的样本与安全的光学II型标识。对14个II类星体进行了分类和X射线光谱分析。由于我们的大多数源的X射线计数（PN探测器）只有1040，我们仔细研究了模拟X射线谱的拟合结果作为拟合统计和分箱方法的函数。我们确定，用Cash统计量拟合光谱和每个箱最小一个计数的分箱最好地恢复了模拟X射线光谱的输入值。在100个PN计数以上，谱线斜率和吸收氢柱密度的自由拟合是可靠的。结果我们发现只有中等吸收（NH =（2− 10）× 10 22 cm −2），没有明显的红移和内在X射线光度的趋势。在少数情况下，不能排除康普顿厚度的吸收体。发现了两个没有X射线吸收的II型物体。我们发现没有证据的内在分离I型活动星系核和高X射线光度II型类星体的吸收。14个II型类星体的X射线叠加谱没有铁Kα线。与此相反，8个II型活动星系核的叠加显示出一条非常突出的铁Kα线，其能量为6.6 keV，EW能量为2.2 keV。
Aims. We present the results of the X-ray spectral analysis of an XMM-Newton-selected type II QSO sample with z≥ 0.5 and 0.510 keV flux of 0.3− 33× 10 −14 erg/s/cm 2 . The distribution of absorbing column densities in type II QSOs is investigated and the dependence of absorption on X-ray luminosity and redshift is studied. Methods. We inspected 51 spectroscopically classified type II QSO can didates from the XMM-Newton Marano field survey, the XMM-Newton-2dF wide angle survey (XWAS), and the AXIS survey to set-up a well-defined sample with secure optical type II identifications. Fourteen type II QSOs were classified and an X-ra y spectral analysis performed. Since most of our sources have only∼40 X-ray counts (PN-detector), we carefully studied the fit res ults of the simulated X-ray spectra as a function of fit statis tic and binning method. We determined that fitting the spectra with the Cash- statistic and a binning of minimum one count per bin recovers the input values of the simulated X-ray spectra best. Above 100 PN counts, the free fits of the spectrum’s slope and absorbing hydrog en column density are reliable. Results. We find only moderate absorption ( NH = (2− 10)× 10 22 cm −2 ) and no obvious trends with redshift and intrinsic X-ray luminosity. In a few cases a Compton-thick absorber cannot be excluded. Two type II objects with no X-ray absorption were discovered. We find no evidence for an intrinsic separation between type I I AGN and high X-ray luminosity type II QSO in terms of absorption. The stacked X-ray spectrum of our 14 type II QSOs shows no iron Kα line. In contrast, the stack of the 8 type II AGN reveals a very prominent iron Kα line at an energy of∼ 6.6 keV and an EW∼ 2 keV.