XMM-Newton spectra of hard spectrum Rosat AGN:: X-ray absorption and optical reddening

被引:9
作者
Carrera, FJ
Page, MJ
Mittaz, JPD
机构
[1] Inst Fis Cantabria, CSIC, UC, Santander 39005, Spain
[2] UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England
[3] Univ Huntsville, Huntsville, AL 35899 USA
来源
ASTRONOMY & ASTROPHYSICS | 2004年 / 420卷 / 01期
关键词
galaxies : active; galaxies : Seyfert; galaxies : quasars : emission lines; X-rays : galaxies;
D O I
10.1051/0004-6361:20035683
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present the XMM-Newton spectra of three low-redshift intermediate Seyferts (one Sy 1.5, and two Sy 1.8), from our survey of hard spectrum Rosat Sources. The three AGN are well fitted by absorbed powerlaws, with intrinsic nuclear photoelectric absorption from column densities between 1.3 and 4.0x10(21) cm(-2). In the brightest object the X-ray spectrum is good enough to show that the absorber is not significantly ionized. For all three objects the powerlaw slopes appear to be somewhat flatter (Gammasimilar to1.3-1.6) than those found in typical unabsorbed Seyferts. The constraints from optical and X-ray emission lines imply that all three objects are Compton-thin. For the two fainter objects, the reddening deduced from the optical broad emission lines in one of them, and the optical continuum in the other, are similar to those expected from the X-ray absorption, if we assume a Galactic gas-to-dust ratio and reddening curve. The broad line region Balmer decrement Of Our brightest object is larger than expected from its X-ray absorption, which can be explained either by an intrinsic Balmer decrement with standard gas-to-dust ratio, or by a >Galactic gas-to-dust ratio. These greater than or equal toGalactic ratios of extinction to photoelectric absorption cannot extend to the high redshift, high luminosity, broad line AGN in our sample, because they have Column densities >10(22) cm(-2), and so their broad line regions would be totally obscured. This means that some effect (e.g., luminosity dependence, or evolution) needs to be present in order to explain the whole population of absorbed AGN.
引用
收藏
页码:163 / 172
页数:10
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